Joel Spolsky has clearly stated that he wants these sites to be welcoming and inclusive where anyone can ask any relevant question even if that question has appeared elsewhere.
With questions being closed in seconds, is the community really being inclusive?
Being able to close questions seems to bring out the nasty side of some people, as evidenced by the snide comments about the use of English that have accompanied some closures. Perfectly valid questions have been voted for closure as "joke questions" by people ignorant of the subject matter.
Some questions absolutely deserve to be closed but shouldn't this be a last resort carried out by the moderators? Closing a question is a strong response, it's really like telling someone to "shut up".
These sites are much more than collections of questions and answers. A real and growing body of high quality knowledge is being constructed which is a truly fantastic thing.
Are there better ways of maintaining the quality of questions other than closing them?
Edit: Many thanks for the responses about the current closure process. I'd really like to know what you think about question closure as a metaphor. Is that inclusive?