IMO, it's more elitists than trolls. I use SO more like a complement to Google rather than a Q/A platform because it's hard to break into the community as a low-karma newbie. It's very discouraging when you ask for help nicely, provide context to your question, and try to contribute back only to see your question immediately closed or the only replies you get are unhelpful or self-serving. Why even bother to put in the effort of asking a question when you are seen as the pool boy at a country club to everyone else.