@Teal I described it similarly to a friend a while back.
Less a debate on the verge to a fistfight, more like sitting in a library with a few people reading books, smoking pipe and now and then someone makes a witty remark and is rewarded with an appreciative nod.
This is definitely a factor.
I also think that the different instance "topics" play a role, which gives more a sense of "community" and less of everyone for themselves.
And then of course "the algorithm" aka "optimization for conflict".
I think it could be interesting to "simulate" several algorithms in fedi (only as experiment of course, not as a permanent addition):
I am not sure how many people grasp the full extent of manipulation due to the Twitter algorithm. I'm not sure I do.