Facebook is not a competitor to twitter. It is culturally just a dead space. Nothing interesting happens there, I can't think of the last time an interesting subculture or meme originated on facebook. It's this bizarre place where you're surrounded by old people but at the same time you're subjected to infantilizing speech restrictions that make you feel like you're in some kind of adult kindergarten or something. You can't make fun of journalists or do anything subversive or culturally alive, it's a place where there is no fun allowed.