Words have import. They form our laws. Definitions have meaning, and this meaning translates to legal rights, protections, exclusions, etc.
If we allow anyone at all to call themselves a woman, and I want a smear test from a woman (which I do), I can't actually be sure that when I ask for one, I'll get one. There was recently a case where a woman who insisted on a female HCP for her smear was held up as an example of unacceptable transphobia. This isn't an anomaly - this is Greater Glasgow Health board, the NHS.
The result? I no longer have smears. There will be plenty more like me.
The end result, of ceding the word 'woman', is that women who are fine sharing with transwomen in changing rooms, toilets, breastfeeding groups, hospital wards, sports, etc, will be not bothered by it. Any women who don't wish to share with male bodied people will either be excluded or exclude themselves. That will include women of various faiths whose tenets preclude sharing spaces with males, it'll preclude some women who have traumatic experiences at the hands of male bodied people (at least 20% of women have experienced rape/sexual assault, last figures I checked). It'll also preclude any women who just doesn't want to be in a small space with a male who does - statistically - present a threat, even if that threat is small. I chose a female driving instructor, for example, because being in a confined space with a male stranger makes me so stressed I couldn't actually get through a lesson.
How is it that the language and the whole of society is shaped to suit this transwoman, to avoid suffering for them, while the women who are at completely equal risk of being excluded, frightened, triggered, traumatised and - remember, I'm talking statistically - attacked, don't have their suffering acknowledged?
When women have raised these issues they've been accuse of 'weaponising' their trauma. Quite the most sickening thing I've heard recently. An MP - an MP! has accused JKR of exactly this.
Why is it no TRA organisation is accused of 'weaponising' suffering when they refer to suicide ideation, and all of the things that transwomen are apparently in danger of?
Why does the suffering/desire/deeply held belief of a transwoman matter more than the suffering/desire/deeply held belief of a woman?