This is only true if your private information is visible to your friends. I don't feel compelled to put anything in facebook at all except the stuff I'd normally put in a public-viewable blog. My profile is 100% blank except for my profile picture, which is a monkey in a nice wool coat.

The only reason I actually use facebook at all is for party invites, if my friends could find a different way to wrangle party invitations I'd dump my account like it was myspace in 2007.