> If Facebook is such a problem then people could just stop being part of these social circles. It really isn't that difficult.

No, it actually is that difficult, or more precisely that undesirable. Very few people are such anti-Facebook activists that they're going to dump valued friends and acquaintances in order to dump Facebook. That's why Facebook is going to hold on to a lot of users, and why it'll end in a whimper and not a bang.

The only case where it "really isn't that difficult" is if you have no valued relationships that have a Facebook component.