The issue with the Mahomes hit is he stopped right on the sideline basically waiting to be hit. The hit itself was rather soft IMO and of course he sold it by flinging himself out of bounds. But overall, I agree with your main point. The game sucks when the starting QBs go down.
Mahomes as made a career of doing it, he uses rules designed to protect QBs to fake out defenders and squeeze out a couple more yards
I'd level him every single time he did it, and use a locker room pool money to pay for fines until he stops doing it, because its complete bullshit