The current New Zealand government is the first in 26 years of MMP where a party gained a majority alone. The previous was made up of 3 very different minority parties. In every other election, the largest has sought the support of smaller parties to govern. I can’t speak for other countries, but MMP has not lead to instability here.

> All systems lead to two party systems

I don't think that's true at all:

https://en.wikipedia.org/wiki/Federal_Assembly_(Switzerland)

It’s not true - it just seems inevitable when you’re within the 1 person, 1 vote and winner take all system of the US.

Score Voting where candidates are given a score 0-99 transcends bicameralism when averages are taken, similar to scores in the Olympics. And it is the superset of all voting methods.

Parliament seat count for parties in Finland [0]:

40, 38, 38, 31, 20, 16, 10, 5, 1, 1

The 4th largest party with 31 seats was the largest one in the previous parliament.

[0] https://en.wikipedia.org/wiki/Parliament_of_Finland

If you believe that someone voting for whom they believe in is splitting the vote, then you don't believe in democracy right? You are thinking like a marketing strategist it sounds like.