Anybody who insists the parliamentary/multi party system is somehow better for the people of a given country need only look at…basically every country that has that system…to see that that isn’t necessarily the case.
“Let’s switch to a multiparty system, that way we can have four parties pretending to give a shit about us while catering to the demands of the rich instead of just two!”
The 3rd parties in the US are only on the side of the little guy because they are also the little guy. If you put them into power they will not stay on the side of the little guy.
Ranked choice voting would make a far bigger difference, as that would allow a greater diversity of opinion both within party platforms, and in the voting booth. And would also allow more 3rd party candidates to have an actual shot at winning elections.