Let's say you are right. You can only compare students from the same class if a curve is used. And then, it doesn't tell you anything about competency. Just if

Let's say you are right. You can only compare students from the same class if a curve is used. And then, it doesn't tell you anything about competency. Just if they were better or worse in that small cohort. If a class is filled with C and D students (objectively), the curve will spread them out and those C's become As. If a different class is filled with A and B students, they are spread out and those B's can fail or become C's. Now the first group's curve A's are not as good as the second group's A's, and are, in fact, worse than the second group's F's or C's. I often set the curve in my classes. I was offered money to not do my best on exams because of how it affected other's grades. My ability or lack there of should not affect another's grade which should reflect their demonstration of subject mastery.