Well, it certainly doesn't help, and to your point, it means there are fewer incentives to overcome it, whatever is driving it.

One of the issues specifically related to your conundrum is that First Past the Post (and I'm speaking pretty generously here and trying to keep a lid on my cynicism) requires that the parties make appeals to very different constituencies in advance, and try to cobble together coalitions that are at least not ideologically ludicrous bedfellows. Serious policy debates do happen in America, but they happen before there is an elected voice advocating for them (which causes its own problems, looking at you, Dems relying on Roe v. Wade to keep the issue settled).

If there are conflicts within your big tent, you have to either accept the cognitive dissonance and hang together to avoid hanging separately, or you simply shout over and over that there's no cognitive dissonance at all, and all these things are part of a cohesive single platform, possibly divinely inspired. Both parties engage in both strategies, though I daresay the Republicans have skewed quite far to the latter, and as their natural power base has aged they've invited people into the tent whom they were previously content to ignore or at least quietly take for granted.

When you declare loudly that all your issues are important, they tend to seep between interest groups, because after all, relatively few people are truly single-issue voters. You can end up with, for example, people who may have little sympathy for LGBTQ+ rights, but no particularly strong animus, actively leaning into opposition they should barely care about, because it is part of "being a Republican," even though what they really fear is the economic anxiety of stagnant wages and perceived inefficient use of government resources, which leads them to think they'd be better off paying less in taxes. Wouldn't it be less bad if they could be part of a right-leaning party with less strident social views who would vote for (unwise, IMHO) tax breaks for the rich but not against gay marriage?

No ranked choice voting, however, means third-party votes are either meaningless or dangerous to your preferred out of the two practical options, and that has the linked effects of directly discouraging your voting for them in general elections, and encouraging the two big parties to find or create or imagine such serious differences between themsleves that anything that helps the other would be disastrous. There are people who, not without some merit, blame Ross Perot for Bush Sr.'s loss to Clinton or blame Ralph Nader for Gore's loss to Bush Jr. in Florida. The system is a mess. People should be allowed to vote for whoever they want without feeling like doing so will result in their worst possible option winning out. Shit, that's basically what I'm dealing with this cycle. I'm personally comfortable enough with the Biden platform, given the realpolitik of the US, to vote for him again, but I'm not enthusiastic about supporting him. Still, I'm more passionate than ever that it's the right choice; I'd be a hell of a lot more understanding of people staying home or voting for other candidates if it were Mitt Romney or John McCain on the other side, rather than Donald fucking Trump.