Yes, of course they do; they have vast amounts of data; click streams, likes, comment text, etc. But I guess I'm saying that the core metaphor, with which Face

Yes, of course they do; they have vast amounts of data; click streams, likes, comment text, etc. But I guess I'm saying that the core metaphor, with which Facebook did much of its early growth, was that two people are 'friends', or are they are not; and that you see the activity of your friends, and sometimes see activity, and get recommendations, from the friends of your friends. They built many iterations of the product, and got a very long way, by exposing a very simple social graph metaphor to their users. Even though that model drastically simplifies the world, it has proven to have a lot of utility for users. Maybe now, because the users are consequently more educated about social networks, a more sophisticated metaphor would go further.