I fought for getting a 4/5 rating at an old job and gave lots of examples. Their argument was that I didn't deserve it because those were just expected. I pointed out my work compared to others in my team and was told that it compares across the company, not the team. I kept causing a fuss about it because I was so angry about it and finally my manager said something about the bonuses has already been communicated and people would be angry to get less. I was confused because I didn't want more money, I was just offended they said I was performing on average when I was going above and beyond every day. It was also really embarrassing to me. If they'd just said the rating doesn't affect anything except your bonus I wouldn't have even cared.
The whole thing is all BS.