Bill Clinton got elected as president with 43% of the vote. The US system with more than two parties would have the exact same issues.

Here's an election in the SDP split largely from Labour; the result was ultimately the Conservatives gaining 10% more seats when their vote share went down https://en.wikipedia.org/wiki/1983_United_Kingdom_general_el...

Both of the last two elections were heavily impacted by Nigel Farage's parties in different ways; gaining very few seats but acting massively to the detriment of Labour in 2019 and even more to the Conservatives in 2024