Quora is just so much better than Ask MetaFilter, Reddit's Q&A/advice subreddits (/r/askreddit, /r/answers, /r/doesanybodyelse etc.), or (dare I say it) Yahoo Answers for nontrivial, factual answers dependent on expertise. Quora is for people who benefit from or enjoy such questions and answers. The longtime existence of all these Q&A communities shows that there is a market for it. There's the most overlap with Ask MeFi I think, but Quora is far better at zeroing in on a good answer, when it exists.