Tumblr Founder and CEO David Karp discusses his company's business model and mobile strategy. He speaks on Bloomberg Television's "Market Makers."I am skeptical about the Yahoo! acquisition of Tumblr, and its efforts to monetize its platform. But while he was cagey a bit, David Karp relates the essence of its business model vis-a-vis advertising: more like TV and print. Not hyper-targeting, not Big Data and analytics driven. But via brands that aim to impact us more evocatively, more sustainably.