Twitter’s new “don’t @ me” option is sending the messaging service into an existential crisis: What is a public social media site without a little back-and-forth?

On Wednesday, Twitter announced it would give users the power to silence any replies on individual tweets. The feature was called “don’t @ me,” named after the playful phrase people often use when sharing a provocative thought—“don’t at me.”

Now, Twitter users can make that official by selecting a setting to limit replies to a tweet, either to no one, only followers, or only people mentioned in the tweet. The feature is currently being tested with a limited number users, the company said.

Not surprisingly, the new feature set off plenty of replies on Twitter, with some people welcoming the control and others wondering if it defeats the purpose of the public platform.

Some people tweeted that it would stymie open conversation if any user could prevent others from responding. Limiting replies could turn Twitter into a more private affair, some people worry. One of the benefits of Twitter is that every user has the same opportunity to speak, regardless of follower count or status.

Ana Milicevic, co-founder of Sparrow Advisors and a frequent Twitter user, believes “don’t @ me” could stoke resentments and lead to even worse behavior, the kind that Twitter wants to limit. “They built a whole solution to unwanted replies by actively encouraging pile-ons,” Milicevic said on Twitter. “I'm honestly amazed at the ingenuity.”

Milicevic said that a person who is spurned would just lash out somewhere else on Twitter. One of the limits of “don’t @ me” is that people could still retweet the comment, and then others could respond to that retweet. (A retweet is when someone forwards a tweet to their followers, a reply is just a response to the original tweet.)

Twitter has been trying to limit abusive behavior for years, dealing with a toxicity that has been deeply ingrained in the platform. People have been chased off accounts by online trolls, and brands have been hounded at times by negativity. Last year, Twitter made it possible for people to hide replies that offended them.

On Wednesday, Twitter called out “reply guys” as the types of users who could be prime targets for the “don’t @ me” button. A “reply guy” is the type of gentleman who mostly responds to tweets from women, offering unsolicited advice and condescending wisdom.

But Twitter also said the feature could be used for more positive reasons, like sparking a private conversation that could still be visible to everyone else. “Beyond limiting ‘reply guys,’ this allows the person tweeting to host fireside chats, interviews, and other types of invite-only convos with just a small group or single person,” Twitter said in its announcement.

Twitter is not alone in its quest to clean up the service from unhealthy interactions. Just last week, Facebook-owned Instagram unveiled a set of tools that give users more control over comments, too.

Twitter wasted no time trying the “don’t @ me” feature, sending tweets from its own account to show people how it works, while also doing a little Twitter trolling: “Reply if there’s a better app,” the company said.

Of course, replies were off.