i've seen way too many threads saying "i'm a noob and didn't want to start this thread please close" so think that this feature would help greatly in the amount of useless threads were other users would proceed to flame at the thread starter for being a noob.
there's just as much of a chance, then, of a member closing a thread after their problems have been solved when the topic could still be relevant to other posters. in such cases, the mods would have to take extra time to come across and re-open the thread. mods do close the threads, and even hide them, something no non-mods/admin would ever be allowed to do. flaming is against the forum rules, anyway. those who do it get punished. when a thread is requested to be closed in such a manner as you describe, no other posts are necessary unless this becomes a common pattern of behavior from the original poster.