The real problem that causes it is, of course, that now we are not allowed to have a word for individuals who belong to the biological sex which typically produces ova.
If 'women' and 'girls' are abstract identities, then we now have no name for that group of people which is the basic group one needs to be in to menstruate (though not all members of that group menstruate and none do all the time). And we have no name for those female people who actually identify as women because they live with female bodies and that affects how others treat them and also their lives directly.
'Women' and 'girls' cannot now be used for that group, so everyone in it has had their identities erased. Moreover, it will be pretty hard to fight against sex-based discrimination, sexual harassment and so on when we have no name for the group most likely to be its victim.
When people talk about 'inclusiveness', they add those who are female but identify as something else to the group by calling the group 'people' or 'bleeders' or 'individuals with a cervix'. But that makes the giant assumption that nobody's gender identity is based on their actual biological sex.
I think (based on my informal surveys) that the latter is almost always the case, so erasing 'women' and 'girls' as names for biologically female people then erases the names for the vast majority of people who currently call themselves by those labels. So inclusiveness invalidates the gender identities of the vast majority.
I no longer can tell if I am a woman in this new system as I have no idea what an abstract gender identity might be, and all suggestions about how to give 'women' and 'girls' an alternative definition are deeply sexist and take us back to regressive sex roles.
But the difficulties this change will cause in the global fight for equality between the sexes is my real concern. And the fact that worrying about that giant problem is labeled bigotry.