That is certainly a valid point. Mostly what happens with people on facebook is that they stay on facebook. They play games, they chat, they look at pictures they stay on facebook. When you goto a movie the ads don't have websites, they have facebook pages. Facebook has created a new type of internet, a more closed siloed internet (Dave Winer reference). People used to use the internet, now they use sites.

The new layer is data locked into private site that farm content.