You’re right that people can write hateful, divisive and othering content with many words. The trouble with the short content platforms is that you can’t do anything else.
EDIT: I realize you specifically called out politics here and that makes me even more inclined to agree.
I’d also add that no one (again, relatively) reads anything, anymore. A couple of paragraphs and you’ll see your engagement drop off a cliff. But a quick, “witty” slap? A stupid pun thread on Reddit? Easy money.
I think your point is generally right - not trying to disagree, but I think these platforms are simply effective tools to mirror back their users and what their users want, rather than the inherent, specific problem themselves. That is, it’s not Twitter that’s the problem - it’s that Twitter users really like the behaviors Twitter rewards.
I'd agree MBP are poor media for nuanced debate but can work well for info broadcasting.
Pre-echochamber Twitter was an excellent venue for disseminating important news - news that actual news orgs were too distracted or deferential to publish.