Okay but your ideal scenario is not our current reality

The reality is that the US Federal government currently has elected members belonging to neither the Democratic nor Republican party [1] [2] (Sinema doesn't count since she changed her party after being elected). This has been true for the majority of the US's short existence.

There is no reason to make long-term decisions based on the current short-term circumstances of a two party dominance.

[1]: https://en.wikipedia.org/wiki/2018_United_States_Senate_elec...

[2]: https://en.wikipedia.org/wiki/2018_United_States_Senate_elec...

All of them caucus with one of the two major parties. As with so much in politics, it's a distinction without a difference.

Two-party dominance has been a feature of the American political scene since before the Civil War - that is, for most of its existence. I wouldn't call that "current short-term circumstances".

It's also very hard to change because both major parties benefit from the existing system and are protective of it, knowing full well that proportional representation would cost them a lot of votes. Republicans usually trot out the old "but small states!" canard, while Democrats are getting creative and claiming that IRV and RCV are racist because e.g. "majority voting may seem innocuous, but if the vote is racially polarized, “runoffs discriminate against Blacks because they are a minority of the voters.”"

Given that Congress has the final say on how federal elections are run, I find it rather unlikely that this is going to change anytime soon - at least, not as long as federal politics is consumed almost entirely by polarization and voting against rather than for.

> Two-party dominance has been a feature of the American political scene since before the Civil War

Really, since America had a meaningful national government with the Constitution rather than being a loose federation of states under the AoC.

The Federalists and Democratic-Republicans both were establisged, as was their duopoly, by 1792.

Indeed; I just didn't want to get into the whole debate about whether the replacement of the Whigs with the GOP as the other dominant party was a meaningful change or not. But it's safe to argue that the present system, including the specific parties in question, has been around for >160 years now.