Mayer seems to view Yahoo primarily as a place where you can find all sorts of stuff on one giant app. “Once the user’s in that app experience, the easiest thing to do is stay in that app experience,”.

I think this is a very insightful analysis. I think there are people that like the "yahoo" way of presenting applications. It may look old fashion to others, but there is a market. If it was not the case, yahoo would already be dead. If yahoo changes its mind to do the same as others, they would lose their soul and die. We have similar experience with RIM that left professional phones with keyboard to become an Apple follower. RIM is (almost) dead.