this is an underappreciated truth, but they quite clearly control the party

Moderate Dems don't represent the Dem party either. But they control it.

Both parties are controlled by the most rightwing factions, even tho most of the voters don't like it.

So we end up with most people voting against someone and not for anyone.

That's how we end up with 2/3s if the country not being happy if either of the two main parties win.