Removing protections for dealerships isn't about increasing efficiency: automakers simply want a larger share of the profit. These corporations wouldn't be clamoring to kill dealerships if they were going to take the profit out of selling cars.

This is just going to result in capital flight from local areas, directly making them poorer. Unless you're a major shareholder in one of these automakers, by advocating for the deprecation of locally owned dealerships, you're advocating for making yourself poorer.