I have heard commentators mention ideas along those lines (never the specific formulations you used as examples, but the general vibe) post 2016, and even a little before that. That is, to me, not the same as that being the policy. Post 2016 democrats needed a cope. They needed a hope to hold on to after they had lost, what to them seemed like a slam dunk. That's not a policy proposal, but rather a strategic observation. In general I think you're better served by listening to politicians when they are trying to build, than when they have failed in building.
I also think it's quite important to note that in that analysis, we presuppose that immigrants will like the democrats. That either requires that democrat policies are good for immigrants, and immigrants to recognize that, or a vast conspiracy to take America down. If demographic change would turn America into a third world country, as some commentators have argued, surely immigrants wouldn't be for that either.
> But I think it's totally fair to say that Republicans have a policy of giving tax cuts to rich people because it inures to their political benefit.
I surely don't hope it's that direct. I think it's fair to talk about the cause and effect, but it would be totally unfair to characterize it as naked corruption. I truly believe that the mainstream American republicans believe in tax cuts as a means to drive innovation. That they believe in slimming down the government from a place of ideology, and not simply a naked ploy to reduce the oversight of their sponsors' activities. That they believe their policies to increase the wealth of the regular American, which they then hope will make them vote Republican.
I worry that this is no longer true of the "far right"/"alt right"/"authoritarian right". That distinction, between doing something for a belief in a better world, and doing it purely for strategy to gain power, is where I place the line to "fascism". A definition I don't share with many scholars.