Companies don’t care about this. They just need some arbitrary scale (5 stars, 10 point rating) and anything less than perfect is an excuse to put someone on notice. Always handy to point to when needing an excuse to trim numbers or not increase benefits. And since nobody is perfect, you can find some arbitrary cutoff that lots of people will be below (“sorry you’re averaging 4.4 stars, we can’t give EVERYONE bonuses now can we”) there’s always room for excuses.