> We have to be honest about the fact that parliamentary systems can give massive power to a tiny fraction of the population when that small party becomes the deciding vote.

The American two-party system gave massive power to a tiny fraction of the population, which the large Republican party then retconned into most of their members as their party platform. Now they're a large fraction of the population. I'd choose the approach where the small faction remains its own small faction, even if they occasionally get to pull the levers of power.