I've been noticing the same sort of behaviour that you're talking about. And while I don't know the cause, I don't think that it's caused by trolls or bots. Instead I'm guessing a few potential factors:

1. Demographic concentration in general purpose, lax moderation instances, tailored to attract your typical Reddit user instead of more reasonable people.
2. Lemmy+Kbin users being proportionally more combative, entitled, petty, and/or whiny, due to how people reached this platform.
3. "Powerjanny" mentality being inherited from Reddit, specially given the likely higher proportion of former Reddit moderators here.
4. General lack of mod tools, forcing moderators to take sub-optimal decisions on how to handle users and content.
5. Normalisation of witch hunting, making people walk on eggs to avoid being confused with witches, and assuming that the ones not walking on eggs fly on a broom.
6. Normalisation of stupidity, and subsequent normalisation of oversimplifications, assumptions, genetic fallacies, phobia against uncertainty, decontextualisation, etc.; with those things either making the stupid act in a hostile way, or others act in a hostile way towards the stupid.
7. Natural reinforcement of behaviour in social groups.

This is already a rather large wall of text and I'm trying to be succinct, but feel free to ask further reasoning on any of those points.