I don't get the "negation of territory" thing either, because I'm not like that and I'm not friends with anyone who is.

I honestly think it's a product of low self-esteem -- that's the only thing I can think of that would make someone need to control who someone else interacts with and what they do so closely, that they're afraid they'll lose the other person. Of course, I've always sort of thought that was silly, but it's the best reason I can come up with?