We wouldn't bother to define 'man' and 'women' if humans reproduced asexually.
Nail on the head.
Whatever Genderists might think they believe, ultimately in practice their vision is entirely based on so-called "cis" people being exactly the same as they are today, keeping all the sex-based structures and indeed sexism in place, but just letting a handful of special people pretend they are actually the opposite sex.
They do not in reality want the open, gender-fluid world they claim to, because how can special people be gender fluid or trans if there's no boring old "cis" people doing sex-based differences like always for them to identify into?
There's no honest intellectual effort to reimagine a world where "men" and "women" actually are mixed sex gender identities and what single-gender provisions (should we even need any) might look like in practice, it's just literraly "Well they'd be exactly the same as we do for women today, only we'd let some cocks in"
So little ability to think through the implications of what they say they believe. So little imagination!