Whether it is closed or not, the result is already obtained, so what the closure is intended to prevent? Other answers? Well, if somebody would write another and better answer, what's bad with it?
Closed questions can be deleted more easily. They also send a message to the other users of the site "this is not how you are expected to ask a question".
Moreover, closed questions contribute to "negative participation score" which can lead to rate limits (e.g., being blocked from asking questions for some time).
So yes, bad questions should be closed, and if no effort is made to improve them, also downvoted and deleted. If nothing else, then to rid the website of their preserve and eventually of users who consistently ask badly written questions.