Most Americans don't have the option to vote for AOC or Joe Manchin (nor for their ideological equivalents). Neither for congress, nor for the President. They get shit candidates and still vote for them because the only viable alternative is an even worse candidate from a party you hate more than the other one. This is very much by design of FPTP, because it prevents third party competition from posing any threat to established parties. The two parties just pick their ideologies from a list of hot topics and never face any competition for the implementation of those ideologies.
This is very much not the case in more proportional voting systems, which provide true political competition across the political spectrum, not just superficial ideological posturing that isn't subject to competition. This is all very well known both practically and academically with tons of research to back it up. Youtube and wikipedia have all the mechanics, the references, and real world data, spelled out.
> Just that what a 2-party system lacks in superficial variety it may more than make up for in internecine disagreement
Sure, a political duopoly is better than a monopoly, but just like in other markets, only slightly so. Political power is a market like any other market, and needs significant competition from more than a couple actors to produce outcomes that are best for the consumers (voters). Even that AmEx case is a prime example, a direct result of shitty parties produced by this shitty election system. And that result will stay here for decades if not forever, regardless of which party is in power, because this election system is not going anywhere, and will keep producing such results.
