Privacy isn't just about hiding my data in general. It's also about hiding it from certain people. I'm not sure why you haven't considered the possibility that

Privacy isn't just about hiding my data in general. It's also about hiding it from certain people. I'm not sure why you haven't considered the possibility that I don't want the government to have my data from an entire collection of web sites, but might not mind any one particular web site having it. More to the point, I worry a lot more about what the government can do with my data than what Facebook can do.