Oh, I see what you mean. I'm not entirely sure why the two disciplines are so different — because I studied medieval Irish literature, I'm more familiar with what it's like on the Goidelic side of things. I do have some friends who research Brythonic stuff, and my impression is that the senior academics in that field just seem to be calmer, more collegiate, and less nasty people. Generally, the tone is set by senior people in the field, so if toxicity is discouraged, it's less likely to flourish.