You’ve read all of your free items this month. To register, get added benefits and unlimited access to articles, Become a Member. Already a Member? Sign in. Advertising Age Article Abstract Tumblr's Karp Vows to Protect Platform Even As Yahoo Ramps Up Ad Biz Founder Walks Back 2010 Comments About Opposition to Advertising; Says He Was Talking About Search By Cotton Delo, Published on May 20, 2013 0 Want more Access, Content & Connections? Upgrade to Membership. We are glad you are enjoying Advertising Age. To get uninterrupted access and additional benefits, become a member today. Register Now Already a member? Log in.