Arthur Sadoun's public coming out as president and CEO of Publicis Groupe was in June at Cannes. There the industry did a collective rosé-spit take over his pronouncement that the world's third-largest advertising holding company would take a year off from all awards programs to shift its spend toward a new AI-powered professional assistant platform called Marcel. Slim and dashing, Sadoun, 46, is now repositioning the holding company as a "platform" with a flat leadership team and a client-centric orientation that has more in common with consultancies than traditional agencies. Sadoun walked Ad Age through his first 100 days—and next 20 years, "If I'm lucky." Our conversation has been edited.

You're the group's third CEO in 91 years. What burden does that come with?
What people do not see is that when you look at the history of Publicis, it has always been in tandem—two people. It was Marcel Bleustein-Blanchet and Maurice Lévy for decades. Then it was Maurice Lévy and Élisabeth Badinter. And you should not underestimate the role of Élisabeth Badinter as chairman of the board. And now it's proven to be working as a new team, which is Maurice Lévy and myself.

So he's still very much involved?
He's still very much involved and the roles are very clear: As the chairman of the board, he is in charge of the strategy. And as the CEO, I am in charge of the execution. We have a long history of working together, of arguing together, of deciding together.

What do you argue about?
I would say 90 percent of what we discuss is client, and on client we never disagree. Where we could disagree is on people. I can find that somebody is great and he may think the opposite.

What is the raison d'être for Publicis in 2017?
This is where I have been working a lot in the last three months: It was incredibly important to redefine what we brought to the market.

How do you do that?
If we want to continue to be a valued partner for our clients, we have to be able to face their challenges with them. And their challenges are very easy: First, low growth. Second, a huge need for efficiencies and cutting costs. Third, brand trust and the difficulty for the brand to be trusted.

Has adjusting to allow for more transparency in the wake of the rebate stuff last year put downward pressure on revenue?
No. Transparency is great news for the industry because there is no way we will continue to have valued relationships with our clients if we don't bring back trust. If we are not able to be an indispensable partner for our client in their transformation, we will lose our raison d'être. If we do—bringing in the right level of alchemy between technology and creativity—then the future looks bright.

Is this where we get to Marcel— the alchemy of technology and creativity?
Happy to talk about Marcel, but we need to put it into perspective. There is for me absolutely no doubt that we need to transform. So the first thing we did is make sure we define well our model. Our model is based on two pillars, which is: Marketing transformation—how do you improve, change, reinvent the consumer journey through media, creative and digital—which you can find in some of my competitors. But it's based on the premise that you can't do that properly if you don't transform from within the business model of our clients. And this is where we have a unique place.

You're reinventing the business models of your clients?
You can't say to a client that "we're going to reinvent your omnichannel strategy, and we're going to build a consumer-based approach," if you don't work with them in reinventing their own model.

In other words, acting more like a consultant.
Exactly. And so the question is how can we continue to be their trusted partner in what is our raison d'être: creativity, putting data at the core and transforming their marketing model while enabling them to do that fast in an efficient way and for the long term by partnering in reinventing their business model. We work with the CMO on the creative and marketing part. And we work with the CIO on how we can link one with the other to be more efficient. This is a unique model. No one else can do it for the unique reason no one can be credible on both sides. You have WPP, Omnicom, IPG, that could work on the marketing side. Sometimes we're better, sometimes not. You have the Accentures of the world working on the digital business transformation part. But none can link both.

And you don't think the consultancies pose a threat when they start acquiring agencies?
If you look at what Accenture is doing and the price they are paying for some creative agencies, you understand why this is the future of our industry: You have to connect the consumer part with the enterprise part.

Talk about the internal cultural challenge of this repositioning.
It is a huge challenge. How do you bring people together? It's fun to see that in the same week we win against Anomaly the Diesel business globally, and we win against all those system integrators for the experience of McDonald's with [global consulting and technology services company] Capgemini. The same company is doing both.

Why is that important?
At the end of the day, it is an integrated team.

You've said you want Publicis to be a platform. What does that mean?
Platform is a French word, so I can give my own definition! First, a platform is a flat organization. What we have done is put together a management committee that is running 100 percent of the P&L and is taking all the decisions. And this is a big difference with the other holding companies: I am not making the decisions alone.

One of my reporters says he heard that the idea for Marcel came to you when you visited Sapient in India. Is that fair?
No, it's where I made sure it could work. [Laughs.] We want to be the one who will reinvent this category.

Why? And how?
Because we have never been more needed than today. We did Marcel for our people. The new generation wants a very simple thing: They want to be able to do things, to produce. They want to be able to have access to more things and influence more things. They want to be recognized. We are bringing to life a platform that will give the new generation an opportunity to do more. We believe Marcel has a role to play as a disrupter of the category. It's easier to wait for some things to change than to change yourself. The problem is if change happens faster than you, then you get destroyed.

Do you find that historically, senior executives have not protected creative departments or creative capabilities? You've had increasing workloads and decreasing fees for years.
I don't know. The great thing is that creativity is not only coming from advertising. It's in media, it's in tech. It's everywhere. This is why I love my job, by the way. The reason why we will succeed is that we will, most of all, put creativity at the center of everything. You can go to a consultant. What makes a difference in a good relationship is the product you bring. We are here to deliver an idea that will change the future of a company.

You're casting this as your differentiator.
Maybe what is different from me and the other holding company CEOs is I am the only one who has been in the creative business. I come from the creative business. And I value, first of all, creativity and the ability of creativity to deliver the value our client needs.

Are you saying that because you want your creatives to know that's what you value, even though you're not going to be submitting for awards?
I think it has been overblown. Not going to Cannes one year does not mean we are changing our strategy. I heard from some that I am not standing for creativity. But I'm not going to CES either, so I am not standing for technology? [Laughs.] It exploded in a way that is interesting: If, for an entire week, people have nothing else to talk about other than Publicis not going to Cannes, it means that our industry is having a problem that is much bigger. I didn't respond to any of the attacks, but I was laughing.

What about internal pushback?
You won't find one big creative that said something against Marcel. Was the way we did it perfect? Of course not. And by the way, I was sad it became a debate about Cannes or not-Cannes, where the debate should be on where [we] are leading our industry.

Has Cannes gotten too big?
It has lost its focus. The focus should be creativity. And I think it's a mistake to say it has been too much driven by the tech companies. Yes it has, it's true. But that's not the issue. I have been to Cannes for 20 years. You were there to see what is the best of the best and the leading edge of creativity and of our industry. And you would leave the place with a clear vision.

This was my first Cannes and that's not what I left with.
That's my point. You can't afford to bring all those people on the Croisette if it's not to get that. And Cannes has to be an agent for us to understand the change we need to bring on board.

As media becomes more automated, what does the role of the media agency become?
The great news about that is, yes, media is getting automated, but the role of media in this complex world is more important than ever. You can't make a difference today between the brand and the experience. Media is playing a key role. Because through the right management of data, you can actually be much more efficient in what you do. We can be much more daring in the work we sell.

Thoughts on the Facebook/Google duopoly? Friends or foes?
They are great partners. When they go for our talent—and when they go directly to our clients—it's creating a competitive environment that I hope we can resolve because we have more to win together than to try to fight against each other, knowing at the end of the day we don't bring the same kind of service. We don't bring the same product.

Or the same scale.
It's true they are a bit bigger. I will have to agree on this point. [Laughs.] They are not credible to talk to CMOs and CIOs together in the way we do. They are bringing part of the answer on the marketing side. But just part of the answer.