According to what, your gut? If you're going to keep insisting that companies "must" do this or that, you need to cite the law that requires them to do so.
Is facebook a company with dominant position?
Anti-trust laws require far more than just being popular to apply and there's nothing in them that applies to Facebook or any other website. Anti-trust laws in the U.S. have never successfully been used against a website because the very notion is absurd.
Yeah, I'm gonna bet on me and my law degree for being right about that. Whether Facebook is in a dominant position is for the court to decide.
You on the other hand are a funny... dude. Haha, "dude" he says :)