I honestly never have understood why someone takes time out of their schedule to belittle people on sites with non-answers to questions.
Very often with these question-answer sites (or, really, any discussion forum - I remember running into this in my newsgroups days) people simply get annoyed at the question being merely asked (like, do they expect everyone else hanging around are as knowledgeable as they are??), and instead of answering the actual question and asking any follow-up questions for additional context that may have been left out of the original question (to perhaps offer an alternative answer later), simply lash out with "RTFM" style non-answers, either outright aggressively, or in a passive-aggressive manner (or by using some other subtle but "polite sounding" jabs that are meant to insult).
I've been a victim of these, but I've also been witness to others doing it. In both cases, it always annoys me enough to not bother hanging around any further (as I'm sure many others also do), which typically results with the place being a swamp of trolls ready to pounce on unsuspecting newbies (Apple's "discussion forums" come to mind).