On the flip side, when you do define these things formally, you end up with those who can and will game the formal rules more effectively outperforming those who don't. This isn't fair either, and there are probably all sorts of biases in who is willing and able to game such metrics (for example, I have seen men game them more often).

Evaluating performance is tough. Evaluating performance without greatly distorting incentives is much tougher. I agree fairness should be a consideration, but it is not the primary purpose of a business.