It really doesn’t go both ways. The winning presidential candidate needs to get the most votes, and most US voters are not progressive. They’re moderate, or indifferent.

I don’t know how you could say that about HRC and Sanders. That’s not even a hypothetical: they literally had a head to head match where, to my huge disappointment, HRC won. Protesting HRC helped elect Trump, and obviously that hasn’t been good for progressive interests or democracy.