Privacy isn't the level of secrecy it's the agency you have on choosing what and with whom to share information.

Reducing the ability to share information is just as much a violation of pricacy as some one "stealing" it and disclosing it them selves.

The problem with Facebook and the likes is that by default anything you post to them is no longer yours hence no longer private and no matter how much security options they give you the potential loss of privacy is the same.

One of the major issues with this debate is that people equate anonymity with privacy and as a positive thing, confuse privacy with secrecy and can't agree if all they want is effective privacy or principle privacy.