To be clear, I used that example because it was the only one I could think of, not for some rhetorical reason (which serves your point anyway, really).

I agree if we could just distill "here's your objective good-at-tennis score" for everybody and draw lines using those numbers, that makes sense. It feels unrealistic? I.e. we already don't do that - it doesn't necessarily feel like 100% an anti-trans thing (orthogonal obviously to the large amount of anti-trans sentiment that generally exists). Maybe Elo for everything?