Goodhart's law comes in because students who do not deserve good grades still can get them via other means besides than the professor intended. Hence grades bec

Goodhart's law comes in because students who do not deserve good grades still can get them via other means besides than the professor intended. Hence grades become less trustworthy (they might lack understanding but "hacked" their way through via cramming etc). However understanding the material also leads to good grades. It's not like there's a trade-off there where students must choose one and thereby lose the other.