This question already has an answer here:
- Why Do We Need to Close Questions? 4 answers
If a question is off-topic, unqualified etc. then users should be able to vote to delete it (so that noise is minimized), but I don't understand rationale for closing the question. Closing means no one can add any answers. what does it accomplish? if question is irrelevant then no one will respond. If someone wants to respond, then by definition the question deserves to be kept open and is qualified.