I think what Facebook is very good at is developing features and app elements that Increase User Engagement(TM). Which is some thin PR language on top of the tr

I think what Facebook is very good at is developing features and app elements that Increase User Engagement(TM). Which is some thin PR language on top of the truth: Facebook develops their apps to maximize user addiction and subsequently enact a lot of de-facto peer pressure to constantly expand their install base without them even having to try. Built-in word of mouth plus peer-pressure. Facebook conditions their userbase to need the app in their life, whether because your pictures are all there or because your family is on it, and beyond that it doesn't really matter if they listen to their base. They've got them already. Maybe the userbase thinks facebook addresses their users' "needs" (strong word for it), but that's more of a commentary on FB's propaganda team and black-hat UX than anything else.