People don't have a choice between Facebook and not-Facebook-but-still-has-all-of-your-friends-and-family. Abstinence isn't a choice here any more than shutting off your cell phone service is a choice; true in the literal sense, but only if you don't mind being unreachable to everyone who still has a phone.

And they do have a choice on proactively giving FB more information than just what it infers