The Web is not a community: a huge impersonal city is a better metaphor. User-generated content (UGC) can be valuable (if edited), but chat rooms should be avoided because of participation inequality.
P. Cobb, and H. Bauersfeld. The Emergence of Mathermatical Meaning: Interactions in Classroom Cultures, Lawrence Erlbaum Associates, Hillside, NJ, (1995)