In your laundry list of institutions that are controlled by the democrats, you conveniently ignored the most important: the Republican establishment.
And that is the flaw in the thinking of those who advocate supporting the Republican establishment.
If you were at war, and had one bullet, with the choice being to kill one of the enemy, or one of your own who you knew to be a traitor, you would apparently use that bullet to kill one of the enemy. But more rational people would recognize that the correct choice would be to shoot the traitor. A traitor does far more damage than a single enemy could ever dream of doing.
To support, in any way, the Republican establishment, is to support the very thing you purportedly despise.