"My hypothesis is that rightism is what happens when you’re optimizing for surviving an unsafe environment, leftism is what happens when you’re optimized for thriving in a safe environment."
https://slatestarcodex.com/2013/03/04/a-thrivesurvive-theory...
If you're trying to push as many people as possible to a "survive" mentality, I assume a divided and polarised community helps. Others are coming for your stuff! For your jobs, for your neighbourhood, for your status quo, etc. Make out that your opposition is some ultimate evil.
A more diverse political field and different voting system would likely help. Might stop single issues dominating the playing field? Bring back some nuance.
I think it's too simple to say "the media wants sensationalism" because we all collectively favour sensational content. It suits for-profit publishers, it suits politically active people, etc. But we're making it work for them. We can pretend we're above it, but if @dang let through all the Musk threads on HN, many here would turn full-time arguing in them.
I don't think that's necessarily inherent to right-wing-ism. Left wing politics has also had similar problems, and still does (say, organic food, or the way vaccine denial used to be a left-wing position), but it doesn't seem to dominate the position. Its bugaboos are "merely wrong"; they don't elevate to a movement-wide denial of well-understood sciences or a TV news network devoted solely to falsehoods about their opponents.
Perhaps that's just a way of redefining the terms of discussion: America's issue right now isn't really about right-versus-left at all, but about something else that happens to organize loosely along those lines. Perhaps rightism lends itself better to that, but I'd say that's inconclusive. Certainly left-wing-style thinking was the cause of a great amount of authoritarian violence in 20th century "socialist" countries. And we're left to argue whether that really is left-wing, or whether it's all just no-true-Scotsman.
You're assuming that they believe in the same sets of "real" and "fake" threats, or at least prioritise them similarly.