1) I don't want potentially naked fotos or conversations of my family online. Do you?
2) Regulations and customs change over time. Something ok 10 years ago can be damning tomorrow.
3) How do you maintain privacy of medical and lawyer conversations when anything can be released without permission?
Ironically, I had the same conversation with a lawyer ("I have nothing to hide.") who had teenage daughters. It really didn't sink in until I gave him those examples.