You’re right. It’s not the number of parties. It’s where the separation of this parties is. The system worked great for a very long time until a group of extremists figured out a way to pull the blankets to them a bit more every year. Gerrymandering and lobbying to tip the balance more and more. In sports, when someone finds a loophole in the rules, they change the rules to keep the game fair. In politics, when they find a hole the dig it deeper and deeper. That’s the difference. None the less, the cure t result is two parties so imbalanced that realistically it’s a single watered down party and an extremist party.