Disagree, if you play ranked and don't boost/ dashboard, psr serves as a fair indicator of skill, you can add or subtract maybe 50 based on character tier. For example as a 600 psr tsubaki i would say my skill is equivalent to a 650 psr ragna, because she's harder to win with.
You say psr doesn't have human input, yet it is based on your ability to beat other humans. Play any legit 700+ and I'm confident they will be fairly strong