Grade inflation exacerbates this problem. The straight A student of today might have been the straight B student of 40 years ago. Meanwhile, the student of 40 years ago that was exceptional in some subjects but mediocre in others can today only get an A for exceptional work, but may get a B for what used to be C level work. Truly exceptional work does not pay in grades anymore, only reliability.
Now, reliability is a very important skill, but it should not be the only thing measured .
That's a good point; I nearly doubled the next highest score on the midterm in a class of mine. I was not even remotely the only student in the class to get an A.
Now, reliability is a very important skill, but it should not be the only thing measured .