The most important thing about the partisan argument, Democrats blame Republicans, Republicans blame Democrats, is not that it is dishonest.
It's that it's functional.
It keeps the population's political energy inside a closed circuit.
The argument is real.
The emotions are real.
People genuinely believe their party would do it differently.
That belief is what makes the circuit work.
If people knew the argument was going nowhere, they would stop having it and start asking different questions.
The argument must feel meaningful while producing nothing.
This is not difficult to engineer in a media environment where both parties have incentives to blame each other and neither has an incentive to question the institution both depend on.
You identified the circuit.
Most people are still inside it, generating heat, going nowhere, every four years, right on schedule.