I find that most forums or other discussion sites I try to join are always much too grounded in their own “cultures” for me to ever be a part of. And such “cultures” usually require you to be proficient in the knowledge of memes and other internet related phenomena to be a part of it. If you don’t assimilate, you will be ignored for the most part.
Granted, I’m talking about video game forums…and frankly, gamers are the worst fucking lot on the net haha. I can never seem to care enough about a forum’s worth and its denizens to take the time to properly understand the community and be accepted. I know I can do it though, as I have done it before. I prefer horror movie forums, fans are usually much more laid back and friendly. Incidentally, I imagine a lot of new users join Fluther and find it intimidating because of the close knit community.
But it really depends on the place itself. Sort of generalizing above, but most places do have their own flavor, plus it also depends on how strictly, or not, rules are enforced. Again, look at Fluther with a newbie’s eyes. If I was new today, I would probably not stay here. I’m glad I joined back when we had four times as many people, therefore more variation.