The problem with Facebook was never what you posted about yourself. The more nefarious thing was that
other people, in theory your friends but more like people you know for whatever reason, could post information that was linked directly to your tangibly real identity.
In the era of the freeform Wall this was pretty silly stuff, but by the time it expanded to picture tagging and the news feed it started to get quite a bit out of your control. You could opt out of some of these things, but doing so generally made you seem a little asocial.
The real diabolical thing about Facebook was that it combined general social anxiety with on-by-default feature rollouts to coerce its userbase into feeding more and more personal info to the datamine. Expect it to only get worse as the userbase grows to epic proportions... they are sitting on a Scientology-scale vault containing the personal details of people's lives.