A first-past-the-post system ends up in a two-party system, which means a big tent progressive party and a big tent conservative party; which in turn means nobody is fully happy with either option.

This isn't to say that multiparty democracies always function well, either. Belgium basically had no government (as in a party elected with a mandate to govern) for two years, from 2018 to 2020.

We're currently in a minority government situation here in Canada. First past the post makes no sense at all, majority of the votes get thrown out, and the party that actually won the vote didn't get the most seats.