I agree that sexism is at the root of this, but I don't think you can remove gender from the equation
Gender is the means, jj. And it imposes a hierarchy.
It makes sure that women, however they identify, are 'lesser than'.
Women couldn't be educated because they're too fluffy, they couldn't vote because they're too uneducated, and it would basically give their husband two votes. They couldn't own property, or take out mortgages, or bank loans because they were financially irresponsible. They had to take on all the domestic labour, because they are always nurturing. Legal 'conjugal rights', which meant a wife could not be raped, was because women were obliged to provide sex, even if they didn't want to, and men were entitled to take it.
Within my (married) lifetime rape within marriage was completely legal and I could be refused service in a pub, based purely on my sex.
Women have been characterised, variously (and not exclusively) as irresponsible, incapable of education, unable to hold high office, unable to work outside the home, incapable of financial independence, unable to manage their own alcohol intake and need to provide sex on demand - right up until the early 1990s.
Lesser than, not given any power, kept down and used for various services. Oppression.
Any time these women said I don't agree with that, I'd like my gender to be imposed like that of a male, it wouldn't have happened. The only white women have made any headway at all is by forcing through actual laws. The law to stop rape within marriage took 15 fucking years to be approved by a mainly male parliament. 15 years
Gender stereotypes have been used to mischaracterise and oppress women for centuries.
And now suddenly, guess what?
Not only are those gender stereotypes considered innate, they are being reinforced by claiming that sex is not about biology, and women, quelle surprise, are being told they are mean and nasty and not nurturing enough if they object. And they are threatened with rape and violence - the tool of oppression.
The socialisation of women is still being leveraged against them whilst it is simultaneously claimed it can be dispensed with by saying some magic words.
If gender was not a tool deliberately imposed, all these transmen would be the ones wielding the power, instead of still being the ones famous for having babies. And all the transwomen wouldn't have a voice, but be at home nurturing the children and cooking the dinners.
The reason you can't quite see this is because of sexism.