Of course they can post whatever, haha, but it just sends the message of who they are and what they do. They can do whatever, but they can't control what other people think of them.
It's more of a social network thing for me, not really something I like to expose my entire life to. I do delete some people who obviously add me to boost their friend count, but for others, meh, you never know when you might need a social contact.