facebook and the like are pretty much popularity contests. "I have 200 more friends than you do! I get more posts on my wall than you do!" I make an effort to keep people away unless I genuinely like them. Therefore when I made an account on myspace and facebook (deleted each after three months of the former, five or six of the latter) I only ever had like five friends, and constantly would get friend requests from people I hated.
I also don't get the fixation some people have. A friend of mine went through a phase where she had to check her facebook like every five minutes. It was incredibly annoying. I mean yeah there's something to be said for ease of access - you know, you're available to hang out X night and you want to make a general announcement - but you have four hundred people on your friends list and you can't really direct that to a specific group of them. So what's the point? Easier to just chat over instant message or - heaven forbid - pick up the phone (and not to text). The whole thing is unwieldy and awkwardly public, and I really don't understand why people have to check their facebooks once or twice a day.
I hope that made sense. I'm sort of still half asleep and rambling...