Segregation? Apartheid? Ghettoization? Pigeonholing? Compartmentalization? Wagon circling? Zero tolerance? Patrolling, excluding, penalizing, excommunicating?
I read LuLa forums by clicking on two links, neither of which has anything to do with forums, sub-forums, micro-forums, etc. I click on "Show new replies to your posts" and "Show unread posts since last visit." I then read
threads there, based on two things: interestingness of the thread title or who the author is.
I look into forums when I need to decide in which one to post my question or comment. In that case, I actually find the number of existing forums confusing and overwhelming. In other words, I would prefer less, not more of it. The advantage of the current structure, however good or bad it is, is that we got used to it.
Value of a discussion is in its varied points of view. Talking only to those who agree with us might give us temporarily a warm and fuzzy feeling, like comfort food. However, like the latter, it isn't good for our long term (intellectual) health. Reading a thread and coming across an objectionable post leaves us with several options: react, ignore temporarily, or ignore (the poster) for good. No need for "special education forums," "nerd sandboxes," etc.
On the other hand, since we are talking about forum pet peeves, here is mine: quoting a long post, especially those with a lot of pictures or graphs, only to add invaluable and profoundly insightful commentary of our own, the likes of "+1," "Well said," "I agree," etc.