I had to read this twice.

The Founding Fathers designed bothe the Senate and Electoral College as foils for populism: i.e. indirect elections. When these institutions became direct elections, this allowed populism a better chance of success.

One of the guardrails of American democracy used to be the influence of the party back rooms. They could affect the outcome of internal party elections, thereby preventing a populist from rising too high. But both parties opened up their primaries to the people circa 1970.

I don't think there is a short term solution here. Maybe American democracy can bumble along. Maybe USA needs a decade of one-party rule. But the USA does need something for the future. It is time for the people to write a new constitution.