You lose a certain amount of control over your question if other people contribute. If there are no answers with upvotes (I think), you can delete your own question. If the question has answers with upvotes, that means that somebody in the community found something worthwhile in the question, so you need support from the community to close/delete the question.

I agree it's a little weird, but I'm not convinced that it's the wrong behavior. In any case, wanting to close your own question is a rare and weird enough situation that I think it's not a big deal if a moderator (or a handful of 3000+ rep users) needs to get involved.

Did you want your question deleted, or just closed?