Their psyche can't handle the alternative.
There's simply too much despair to swallow if you realize he's controlled opposition for a uniparty, you are filled with hopelessness. So your self protecting psyche does it was does best and protects you with a nice story about democracy.
The truth being there's more continuity between them then not. You get a change in bombastic rhetoric, nothing else.
Trumpers will lap- up the "greatest, most- bestest" bills supported by trump and the frog boiling continues.
Put simply it's a motte-and-bailey strategy. The bailey is put forth by the democrats, and republicans settle on the bailey portion.