JK Rowling expressed the view that people born with female reproductive systems face particular forms of oppression and discrimination and marginalisation, and are vulnerable in particular ways. She said that those female-reproductive-system-people should therefore be considered a social and political class that has a word that describes them, so that their oppression can be articulated, their needs can be addressed and their rights can be protected.
She noted that there used to be a word for this group - women and girls - and drew attention to those words now increasingly being erased from discourse and from law (along with the word 'sex') in order to privilege the view that we all 'identify' as male or female, both or neither, and that the actual biological sex of people-born-with-female-reproductive-systems has no bearing on the life chamces or experiences of those people, except insofar as it makes them the privileged oppressors of people who identify as female despite being born with male reproductive systems.
JK Rowling, like many women here, is apparenly insulted by the assertion that her sex is meaningless and that what makes her a 'woman' is an internal sense of identification with sexist stereotypes. She is also concerned about what it means for vulnerable women in refuges, shelters, public facilities and prisons when the right of people-born-with-female-reproductive-systems to single sex spaces is lost, and they have to share those showers, prison cells, refuges etc. with anyone who 'identifies' as female, even if they have full male genitalia, a beard and only feel womanly on Tuesdays.
For giving some thought and concerns to these issues, instead of parroting "Trans Woman are Women" as if just saying it erases any need for "women" to have an actual meaning, JK must be punished.