I disagree on the last point. Bad posters are bad for the forums. I can't say it much better than what UG said.

Also, this made me think of my high school American History classroom at school. We have LOTS of discussions in my class about all sorts of different things. Four of my five classes freaking rock. I have all sorts of students asking great questions and giving great answers/opinions to each other. It's a sight to see and really is amazing how awesome those class periods can be.

Every year it seems I have one "dud" class, where the "loudest" voices are, to put it in a nice way, not the best or brightest students in the world (not even close for some of them). The discussions in this class are shit for various reasons. All it takes is one or sometimes two bad apples to make the entire classroom discussion go down hill. The smart kids that would normally have great things to share don't, or no longer share because the discussion isn't stimulating for them (therefore not worth having). That, or they know it'll end up in a huge clusterfuck so they have a "why bother" sort of attitude.

If I could get the "duds" out of my classroom so the experience was greater for my other 20-24 kids, I would in a heartbeat. Again, addition by subtraction.
This is my belief as well and the decision was supported by Xianti. Who, in the end, owns and runs this forum as he should see fit.