The American political system is a “two party” system. This fact has, in my personal experience, reduced the entire discourse of politics into a sports match. This might be obvious, but I’d wager a good portion of Americans going out to vote are only doing it because “the opponent is blue and I am red” and “the opponent is red and I am blue”. Sure - Trump might justify good reasons not to vote for him, but many democrats I know would have never voted republican either way, even if the democratic candidate wasn’t to their liking. This essentially means that people only vote to spite the other party. Let’s then consider those groups who do have nuanced discussions over a candidate positions (I’m mostly referring to the presidential election) - even when they are willing to vote for either side, many, most in fact, probably don’t agree fully with any of the positions. But they have to vote! That’s most important! Something often spouted by many. And I agree - to some extent.
Everyone screams to each other about each others party, it’s incredibly easy to create a divide here. But I wager this is much harder to do with a strong, multi party system. Yes, the US has other parties, but the entire system is rigged against them. The political system is a cartel between red and blue, ensuring no other party can capture any meaningful percentage.