User 'potamic' made most of the point I would have made, so I'll address this:
> I get to keep tabs on friends without actively having to reach out. So people don't become strangers over time.
This is a fundamental perversion of the notion of social interaction. It proposes an argument whose form and frame substitutes people and relationships for a passive consumption of images of people and relationships. Instead of people becoming strangers over time (which is normal and healthy), everyone is transformed into simulacra of acquaintances or friends instantly; you are implicitly, automatically estranged from the beginning. Your Facebook-mediated relationships last longer than they would have without Facebook precisely because of its impersonal and inauthentic character which absolves you of the real effort otherwise required to have an authentic relationship.
To use it is to delegate an always-increasing portion of your social existence to the black-box of the Zuckertron, with all of the political, ideological, and economic implications, caveats, and perturbances that come with it. To wit: you've already accepted the argument, and you're here defending it with evidence amounting to 'everyone else plugged into the Borg cube is plugged into the Borg cube, together we all cube the Borg cube'.
Needless to say, I am skeptical that the niche Facebook has carved out for itself as the arbiter of who-and-what-I-see-and-how and who-and-what-sees-me-and-how is likely to work out in my favor.
Recommended reading: The Work of Art in the Age of Mechanical Reproduction, Walter Benjamin https://web.mit.edu/allanmc/www/benjamin.pdf