Facebook does not represent the end of online anonymity because Facebook is one single site. There is nothing objectionable about one site having a rule to use your real name or not at all, and it is the height of entitlement to claim otherwise. (It's popular, so now they have to do X Y and Z)

Doubly so given how granular the controls are regarding who can see what. Sharing on Facebook is a completely opt-in process, so if you don't want your boss seing your pictures, you have a litany of options, including lists, person-to-person sharing, blocking, and not friending them in the first place.

The problem is that this requires a modicum of effort, and people don't want to have to expend that effort. They want to be able to blast everything out there and just kinda hope that it doesn't get them in trouble. It takes effort to use stuff that's not Facebook.