I'm not really sure the Westminster system is that different to what the USA, or Australia or any country whose system is to divide the country into small piece

I'm not really sure the Westminster system is that different to what the USA, or Australia or any country whose system is to divide the country into small pieces each of which elect a single member. They all evolve into two party system. The reason is pretty simple. If your country is divided into say 4 groups 40%, 30%, 20% and 10%, then it's likely highly either the 40% or 30% are going to win in every electorate. The 20% and the 10% won't get a look in. The 40% and 30% then become your two parties, and competition for the centre tends to make them look very similar. If you want you parliament to reflect that 40%, 30%, 20% and 10% ratio, then one way to do it is get rid of electorates. Instead ask the 40%, 30% ... parties to nominate candidates in ranked order, and appoint candidates to parliament in proportion to the votes the party received across the entire country. Mixed-member proportional representation [0] does that in a complicated way, mostly complicated because they keep electorates. It's been remarkably successful for countries that have adopted it, eg Germany, New Zealand, South Korea. And remarkably successful includes financial outcomes. (New Zealand was a mess before they adopted it.) Australia has it for it's upper house, and as an Australian I think that's what keeps the place sane. [0] https://en.wikipedia.org/wiki/Mixed-member_proportional_representation https://en.wikipedia.org/wiki/Mixed-member_proportional_repr...