I'm fairly new here, so haven't much right to comment. But I have been dipping in to Mumsnet (just to read the posts on various themes) and it appears there's more control there and non-acceptance of nastiness. For instance, someone on there started a thread entitled 'Ramadan Nonsense' and it was immediately moderated and the poster required to remove the word 'nonsense' from the title.
For me, the most annoying thing here is when two or three people post in a long and vituperative argument which isn't of any interest to all the others and drives them from the thread. The argument often gets more and more offensive. I personally feel this should be nipped in the bud sooner. However, I really enjoy the discussions in the BS section, and would miss it all very much if it no longer existed.