What is the deal with this "like us on Facebook" stuff?

Now here's the God's Honest Truth.  If there was a "dislike", or even a "despise" button on Facebook, it would get used a hell of a lot more than the LIKE buttons. All I can figure is telling someone to like you on Facebook has gotta be some strange marketing scheme that I couldn't figure out even if I tried which I won't. But ya'll go like me on Facebook, okay?  I think I got an account there once...forget the password tho....anyway.....