Honestly steam as much a social network as a games platform at this point and that's what gives them the data, and we've see. How Apple and googles multiple attempts at social platforms have panned out.
I would argue that point is kind of moot, since many of the ways I discover games on Steam would work without any friends or a social graph.
The sales (holiday, weekly and daily), curators, user tags etc, etc. They would all still work.
They just don't care.
I'm not sure what exactly that would suggest if true, but I think it would be interesting.