i think one major flaw in the narrative constructed in that essay is that it assumes the democrat and republican party platforms haven't changed over time. both parties have moved quite a ways to the right over the decades in question, and the makeup of their constituent bases changed as well.

i definitely think irrationality and demonization of the other plays a massive and important role in the current state of american and global politics, but i also think identifying it as the problem rather than a symptom with many contributing factors is a dangerous oversimplification.