Unless, of course, you're me.
I love Facebook. And I'll tell you why. Because every day I am exposed to information and articles and points of view that are new and different. And every day I wander into discussions with people, generally people I don't know. And every day I pick a side to debate, often not quite knowing fully what I'm talking about, and often pretending to know something when I don't (although I do this more out of ignorance than out of ego). And every day I get my ass kicked at least once by someone cooler, more articulate and a helluva lot smarter than myself. And damn, I'm lovin' every minute of it.
If you don't mind looking stupid, you can learn an awful lot.