I'm not ignoring that, I'm describing what I see is an underlying cause. If online discussion tools respected the principle of setting proper expectations for each communication channel, the problem would be much milder, as the problems you describe would be limited to smaller groups of interaction, instead of being escalated to viral dimensions.
But all the rules in the world can't solve for bad actors - both speakers and listeners.
There's a fluidity to human interaction that rigidity of rule sets will never totally compensate for.
And too many rules can be counterproductive and be empowering to bad actors who thrive in increasing beaucracies, at the least by making it difficult for everyone else so they look good by comparison. Then the whole focus gets lost. More time is spent navigating, adhering to, debating rules than the primary focus...
And trolls love thst shit.
Despite that, for groups where people come from very different origins and cultures, it is better to spell out the expected rules of behaviour to some degree. "No rules" only works when participants are homogeneous enough that all them already know the rules.