I bumped into an amusing post on an inactive blog. In five quick, tongue-in-cheek points, Evan Lenz explains what grading teaches you:
2. An abdication of responsibility
Grading encourages you to abdicate all responsibility for evaluating your own learning. That’s somebody else’s job. Other people know better about not only what you should be learning but how well you are learning it. This is their game, and it’s your job to play it. Why you would want to learn something, what you would apply it to, what meaning or importance it has for you, what enjoyment you get from it—these are completely irrelevant to your grade. So why even pay attention to these considerations? They are a waste of time. They’re not going to help you pass that next test.