Indeed. This seems to be the motivation behind the sale. I'm sure David Karp would have liked to keep tumblr independent, despite the huge payday, but it seems to me that he failed to develop a cohesive business model.

I loved the focus he put on the market sector he was serving, and I share his hatred of intrusive advertising, but he didn't present a realistic alternative. It's a shame - we keep losing innovative businesses that don't think enough about long-term business models, so we have to hop onto the next big thing until it too gets snapped up. Much as I dislike Facebook, you have to respect Zuckerberg for not selling out... at least he's tried to build something sustainable.