I’m not sure it’s even obvious for sports. Doesn’t it make more sense to divide sports by physical ability regardless of gender, rather than use gender as a preposterously imprecise proxy for physical ability?
Why have one team made up of the fastest boys and another of the fastest girls, rather than one team made up of the fastest kids and another made up of the next fastest kids?
Why have one team made up of the fastest boys and another of the fastest girls, rather than one team made up of the fastest kids and another made up of the next fastest kids?