I don't know about other people and Facebook, but this is about me and Facebook.
Had Facebook about three years ago, until I started trying to become astray (Is this the proper word?) of people. So I deleted it, trying to make myself appear as not being connected and all. And for me, it worked. Its not only because of Facebook, but it was a part of the path of cutting ties with regular social relationships, meaning friendships, and intimate (BF/GF stuff) availability.
So not having a Facebook keeps me from knowing about parties and being invited to them, as well as other social events.
So I, kinda loner, do not have Facebook. I don't know about other loners, but I would think that those who seek social relationships will have it, as its maybe one of the most efficient ways to be connected to people (You know how I mean it).