just look at canada.

the electorate is damn near 65%-35% liberal-conservative yet conservatives are still a viable party (and won a plurality of seats in 2019) and still have the potential to form governments in a country where their politics are largely rejected by the majority of people.

because of vote splitting on the left (3 liberal parties).

you have some ridings (districts) where almost 65% of people vote for left leaning parties and conservatives still win that riding because liberal parties get a substantial share of the vote and end up splitting.

like this:
https://pbs.twimg.com/media/EHVD8gLWoAo-K5G?format=jpg&name=large
(cpc is the conservative party and the next three parties listed are all liberal).

thats the equivalent here of 65% of people in an urban district voting for democrats and them being represented in congress by a republican. or a district where the people overwhelming support climate change policies being represented by a climate denier (happens in places like ontario).

now imagine the same thing also happening in all of those american elections where the liberal majority isnt even that overwhelming.

disaster.

it also greatly diminishes the chances of the 2nd and 3rd leading liberal parties getting representation. we saw this in the underperformance of the new democratic party in canadas last election compared to their original projections (they would be the equivalent of bernie progressives here).

theres a great deal of strategic voting that goes on in countries like canada (they have whole websites dedicated to it) that americans just arent smart/informed enough to pull off.

shit we cant even stop fucking up elections when 3rd party candidates only get like 2% of the vote lol.

a parliamentary system here would just ensure that a solidified homogenized conservative party maintains unbridled power over a fractured/split liberal coalition. its an idea that sounds good on paper like term limits...but in real life it would actually do the opposite of what people think it would do.

the 2 party system...under our current/historical conditions...actually saves us from being some minority-party run authoritarian state like saddam husseins iraq or something like that.