[Jensson]

But MMP means that if people are really unhappy with the current system then a new party will appear. Trump wouldn't have been a republican, instead he would have been the leader of the new right, similar to how many such parties popped up like mushrooms all over Europe. They weren't old parties that got reformed, they were new parties created as a response to people demanding such parties.

You are right that such changes are rare, they certainly don't happen once every 25 years, but the fact that they can happen is really important. Otherwise you are left with situations like current USA where many wants to vote for lower taxes but don't want to support Trumps other political views, in Europe you just vote for another right wing party but what do you do in USA?

Similarly you have many people who wants to vote for higher taxes and more government programs, but don't want to vote for all the identity politics. What should they vote for? Now the entire left is associated with identity politics and the entire right is associated with opposition to identity politics, making it hard to distinguish between different views and probably making the whole political conversation way more toxic than it needs to be. It has gotten to the point that people often assume you are racist if you argue for lower taxes etc.