What if I moved out from a neighbourhood because I had enemies there, we didn't like each other? Now I'm coming back to my parents house and facebook reminds me about them and them about me?
It's not unheard of to have people in your extended network who you would rather not have alerted to your whereabouts. Examples: abusive ex, clingy co-worker, mother in law, etc. "Enemy" is a rather melodramatic term but you get the idea.
