If the chips are designed to sacrifice performance for power usage, then they have no place in a computer without a battery.

Apple should assume that desktop machines have an unlimited power source, and that users want a maximum speed. That the users time is more expensive than the electricity being fed into the computer.

Laptops, sure, sacrifice power to extend the battery. Apple does an excellent job here.

The only reason you would buy one of these desktop machines is because you want to be in the Apple ecosystem.