@the winter soldier
One explanation of it that's been on my mind is think of it as a conversation about manners respect and boundaries. There are two competing systems of classifying people both include everyone (ish) and we are perfectly happy to accept that these people exist we aren't saying they don't or shouldn't but the same person might have different words to describe themselves in each system.
So in 'old progressive' people were male or female and the words men boys women and girls were signifiers that showed you were an adult or a child of whichever sex. So simple children could understand. These were (are) broad and inclusive categories no human is poised between the two sexes. Everyone inclusive of possible deformity defect or disorder still belongs to one sex or the other.
And then you can have, sexual orientation: Homosexual Bisexual or Heterosexual. And under the 'old progressive' system this denoted which sex (or sexes) you're attracted to without judgement or pressure to change.
And then there is the extent to which you conform (dress hair make up jewellery etc.) to the gendered expectations the society places on you because of the sex of the body you were born into. GNC stands for gender non conforming usually meant in quite supportive terms as it was recognised that people (men) often suffered backlash or risk of violence for visible non conformity in terms of hair dress make-up and women for not being sufficiently available to men.
But over time heterosexual and homosexual was somewhat supplanted by straight and queer where straight meant something a little like boring / vanilla and queer meant something more like experimental / exciting kinky.
And you got to 'new progressive' - the assertion is that this is kinder, more 'inclusive'. I am not persuaded that that is true...
I shalln't attempt a clear explanation of the new system as even my best effort at clarity would sound like a piss take. But if you can't acknowledge sex women suffer. If women can't talk about our sex you can't talk about sex discrimination, sexual assault, sexual harassment, rape. If we can't use our words to describe our reality women suffer. If we can't talk about our anatomy we can't talk about our health or pleasure or control our contraception. At every turn its women who lose out, women who are silenced and sidelined and treated as unimportant support humans.
And then you get to sexual orientation... The word Lesbian has been redefined and this redefinition embraced by stonewall to mean Lesbian (homosexual women) and heterosexual men (old system) who feel entitled to have sex with them.
IF I thought the new system was better I'd be a non binary pansexual as would my husband. But that would miss out some pretty crucial information.