I think communities attract types of folks unless they become uber popular (like reddit) to the point they can attract everyone. 4chan was interesting when I found it, but I quickly found it became mostly toilet humor at its best, and was often (i.e. every time I opened it) full of racism and sexism. It was a safe place for immature folks to shout whatever they wanted and not care who it affected -- though of course anyone affected likely ditched the cesspool anyways. Yet, as I watched one of my friends continue to use it, I don't think it was pure coincidence that their own verbiage became increasingly vulgar and desensitized. As some of my friends matured as they grew up, I found he went the opposite direction (at least in online messaging).