So far I’ve mostly thought of Facebook as the other Internet.
It’s an Internet that contains all the stuff I don’t really want to know. A site with the handy property that almost everything on it requires you to log in to see it, meaning that I never see any of it and so can’t worry about it. Their login policy provides peril-sensitive sunglasses for the Internet user.
As the reach of their user database and APIs increases, the number of other sites needing a Facebook login increases too, and the proportion available without one diminishes.
But the Internet was inevitably going to fragment and warp. When I started using it, it was still possible to think that the set of one’s peers and potential friends on the Internet was “all the other people who use the Internet”. Now everyone uses it, and subsets of users can expect to use subsets of the Internet. The Internet-that-doesn’t-involve-Facebook keeps growing, even as its proportion of the whole shrinks.