That's not true.
No - recognising that woman is a real category based in biology, that by definition, excludes all men - has not changed many of the problems that women face. You're right in that respect.
But it's not true to say that nothing has changed. Changes have already happened, or will happen, because of the tireless campaigning of feminists.
Changes such as:
Women in prison no longer being at risk of rape from their fellow inmates who are male.
Women not being able to question being body searched by a man - a man with an erection maybe, or a man giving them a strange leer, or a man who terrifies them just because he is a man in a position of power over them. A man who is subject to less scrutiny because he calls himself a woman.
Likewise for women in women's only refuges, homeless shelters. Sexual harassment and assault from males is one less thing for these women to worry about.
A man, generally won't be admitted into the same open ward space, and if, heaven forbid for some unavoidable clinical reasons he is, and he takes advantage of that situation to rape another inpatient - the hospital won't gaslight his victim & mislead the police by denying that he exists.
If you are raped by a man, you wont have to talk about that experience in detail with a man dressed up as a woman, in order to access counselling and support.
You won't have to refer to your rapist, as a woman, though he raped you with his penis, in the court room, after he cynically appropriates a female identity in order to access yet more vulnerable women to abuse.
If you participate in a women's sporting event, and you are the best woman there - you don't have to watch whilst your trophy, medal prize or award is given to a man who is dressed as a woman, with whom you cannot compete due to your biology.
I'm sure I could think of more examples. You are correct - this is a chunk of a larger whole - but women cannot protect their sex based rights if the terms woman and sex are actually rendered meaningless, and they don't actually exist legally as a class. So this clarification is fundamental to women's sex based rights.