Earlier quoted context omitted.
What are the biggest downsides, as you see it?
The tiny minority has tons of power. Think of a three party system with 45 / 45 / 10 of the votes. The 10% party gets to see which of the big party will support their measures. The party that gives in can now have a combined 55% of the vote, and can then railroad through all the laws of both the 45% and the 10% party, totally ignoring the wishes of the other 45% party. So effectively, a tiny 10% party now has more po…
Isn't that exactly what we have in our current 2-party system, with factions forming coalitions against the other groups that they most disagree with?
Might the only difference be that, on one side of the Atlantic, the individual factions have explicit names while the coalitions go unlabeled, and on the other side of the Atlantic we explicitly name the coalitions while the factions they comprise go (mostly) unlabeled?