One party rule always devolves into a race to see who is the most pious. Show Trials were a great example of how that works practically. Those who haven't read up on them may not be aware that only the truest, most prominent communists who fell from grace got a Show Trial. At the trial the person always read a script denouncing themselves as reactionary, or some variation thereof.
Part of America's problem is that we lack true two party rule. Due to geographic sorting, gerrymandering, etc, we have a de facto dual one party system. So it leads to everyone in Oklahoma out-Trumping each other, and everyone in Seattle confessing their eternal sin of whiteness. In places like where I live (Michigan), it's scarcely better, it's just more local, since we don't have a state-wide consensus.
Ideological purity is not a virtue and never will be. I've literally been called a bigot on this very site for expressing the opinion that compromise isn't bad per se. That's the state of play these days. If you can't outflank the guys on your own side, then you're the enemy.