So I agree with you that a government as simple as “majority rules” on everything is a bad idea.

My view, which has also been the view of our legal system since the 1930s, is that counter-majoritarian structures should be put into place to protect civil liberties and civil rights. However, counter-majoritarian structures should not interfere with economic policy. The main justification for this is that disconnecting economic policy from democratic decisions is that that decision functionally chooses the normative preferences of capital over the normative preferences of labor. There is no reason to do this.

The beauty of a competitive democracy is that these economic policies should self-correct. Too much regulation? Voters will vote in free marketers as they did with Reagan. Too much free markets? Voters will choose the progressives from the early 20th century or the options today. But these decisions should be with the people.

And your line about the problem with populism being that it promises the impossible is not really a problem unique to populism. I would argue that the conservative supply-side economic program (cut taxes which will pay for themselves and everything will be great!) suffers from the same over-promising and simplistic thinking. But that is clearly not a populist program.

What you seem to be advocating for is a technocratic government where decisions are in the hands of experts and not with the people (like the Fed). If this is what you want, you should support the Democrats and especially Warren. Their view of the administrative state is that it should be staffed by experts who are somewhat immune to political considerations. In contrast, the Republican Party fundamentally is against the idea of experts in government, and thinks the administrative agencies should be responsive to political pressure.