You are correct, the argument is going round in circles - though how anyone in aviation can think that having an independant check on the one time you get QNH is beyond me.
Pilots checking QNH against threshold/apron elevation is a common sense idea and I'm frankly shocked that it isn't standard or that some pilots might even have to be 'trained' to think of it.
Maybe there is a big hole in basic training - tha sort of thing is PPL level at best!