>Perhaps it's never occurred to the author that people with the opportunity to change the world (a) might not care about changing the world or (b) might think a photo sharing app is the best possible way to do it.

Yet another third option: the people with opportunity to change the world do have the desire, but are working on something else at the moment.

It's a sad fact that the world has an extreme shortage of people with both competence and idealism, because our social system has a strange urge to exterminate idealism at all costs[1].

[1] -- http://www.thebaffler.com/past/practical_utopians_guide