The problem with active/young people market is they are very temperamental to ads, if you don't treat your user base like the tumblr founders have, they would have easily changed to another platform with less ads. Sure if yahoo acquires tumblr they gain direct access to this marketbase but if they tarish what tumblr is now, with a bad ad revenue scheme they will very easily lose that market base to something else.
The situation isn't as simple as you put it. This time, there is single player game that shouldn't need forced interactivity with an internet connection. Compared to a text editor where the internet connection allowed multiple users to operate on it at the same time.