A multiparty systems has some advantages. But it also has flaws and it wasn’t able to stop Brexit.
And I don’t think a multiparty system would have been able to stop the rise of Trump all else being equal equal.
It seems you wish for a system which would be able to stop Brexit against the will of the people.
The uk doesnt really count, because it also has a fttp election system for the parliament, there are always 2 big parties and then some minor ones. Better example would be Germany.
The UK Parliament was by all means a two-party system, with Labour in one side and the Tories in the other. If anything it has become more diverse post-Brexit. Compare that with the Bundestag, where no party has more than a quarter of the seats.