Your theory is just a theory, and a weak one. The evidence suggests that the election was mainly just a backlash against inflation and immigration, as has happened across the world to parties of all stripes. Not much could have been done to avert the outcome. But it is also clear that a bunch of voters were pissed off by what they perceived as Democrat excesses on cultural issues, and apparently many of those people were in swing states.
More generally: "just turn out the base" is usually a losing strategy in democratic politics. For a simple reason: the cost of turning out your own base is that you will fire up the opposing base and turn them out too. To be sure of winning an election in democracy, you will need to get your hands dirty and persuade people. In practice that will mean tacking towards the center and making compromises.
I'm European who votes green. I want the Democrats to win because that is better for the world. If only you did too.