You’re assuming grades mainly exist to solve an industry problem. But why should that be true? If I’m running a school I’ll use grades to further my own school’

You’re assuming grades mainly exist to solve an industry problem. But why should that be true? If I’m running a school I’ll use grades to further my own school’s educational goals and trust the various industries and other post-graduation institutions to figure out how to determine who best fits their purposes for themselves. There certainly is a real value in putting the smartest (well, most able actually, but I know what you mean) people on the hardest problems. So better to use a system designed for the specific purpose rather than try to repurpose something made for a different purpose.