Re: "Facebook doesn’t know who a user is, [..] what their address is, or anything"
I take it you have no idea what FaceBook is working at with its AI. My wife had a FaceBook account for two years or so. FaceBook was regularly asking her to confirm if she lived in a given village, and the name of that village regularly got closer to where we actually lived at the time.
You may avoid giving specific information to FaceBook, but you have friends, and FaceBook is watching their interaction with you, as well as everything you do. Post pictures ? FaceBook is interpolating with pics from your friends. FaceBook is correlating your messages. FaceBook is watching every damn thing you do.
Obviously FaceBook knows a lot more about you than you think.