This discussion has made me think I need to re-read Sheila Jeffreys' Gender Hurts on the topic of sex castes and see how it's holding up. I can't find the relevant part but I've a vague memory that Jeffreys introduces a new hierarchy of oppression in which transwomen outrank women and, somehow, transmen end up in a desperate place. NB: iirc, Jeffreys wrote this ahead of the steep increase in ROGD and young girls/women opting for NB or transgender status.
Quoting from a 2014 review by the deceased Gender Trender (available on some archiving sites).
Sex caste
In this book I have chosen to use the term ‘sex caste’ to describe the political system in which women are subordinated to men on the basis of their biology. Feminists have disagreed over whether women’s condition of subordination is best referred to in terms of ‘caste’ or ‘class’. Those who use the concept of women as a ‘sex class’, such as Kate Millett, are referencing their experience in leftwing politics and see the idea of ‘class’ as offering the possibility of revolution (Millett, 1972). Millett did, however, use the term caste as well, speaking of women’s ‘sexual caste system’ (Millett, 1972: 275). If women are in a subordinate class in relation to men, as the working class is in relation to the bourgeoisie, then women’s revolution can be conceptualised as overthrowing the power of men in such a way that sex class ceases to have meaning and will disappear as a meaningful category (Wittig, 1992). It also implies, as in left theory, that women’s revolution requires the recognition by women of their ‘sex’ class status as the basis for political action. Nonetheless, the term sex class can be problematic because it implies that women could move out of their ‘class’, in the same way that individual working class people could change their class position by becoming embourgeoised. The term ‘caste’, on the other hand, is useful for this book because it encapsulates the way in which women are placed into a subordinate caste status for their lifetime (see Burris, 1973). Women may change their economic class status with upward mobility, but they remain women unless they elect to transgender and claim membership in the superior sex caste. Both of these terms can be useful in articulating the condition of women, but the term ‘caste’ offers a particular advantage in relation to studying transgenderism. The very existence of transgenderism on the part of women demonstrates the stickiness of caste subordination. The marks of caste remain attached to females unless they claim that they are really ‘men’, and only a very significant social transformation will enable change in this respect.
Postmodern and queer theorists share with transgender theorists the idea that ‘gender’ is a moveable feast that can be moved into and out of, swapped and so forth. Gender, used in this sense, disappears the fixedness of sex, the biological basis that underlies the relegation of females to their sex caste. Female infants are identified by biology at birth and placed into a female sex caste which apportions them lifelong inferior status. The preference for biologically male children and the femicide of female infants, for instance, which has created a great inequality in the sex ratio in India and other countries, is based on sex and not ‘gender’. Female foetuses are aborted and female infants are killed because of sex, not ‘gender’ discrimination (Pande, 2006). Foetuses do not have ‘gender’ or ‘gender identity’, because the forces of a womanhating culture have not had a chance to affect the way they understand themselves. The inferior sex caste status of women is assigned with reference to their biology, and it is through their biology that their subordination is enforced and maintained through rape, impregnation, and forced childrearing. Women do not pass in and out of wearing ‘women’s’ clothing, as cross-dressers may do, indeed they may reject such clothing as inferiorising, but still suffer violence and discrimination as women. Though individual women may be successful in roles more usually abrogated to men, they are likely to be treated as interlopers and receive sexual harassment, as happened to the Australian Prime Minister Julia Gillard (Summers, 2013). Her caste status was continually thrown in her face by hostile male commentators, politicians and cartoonists. Women do not decide at some time in adulthood that they would like other people to understand them to be women, because being a woman is not an ‘identity’. Women’s experience does not resemble that of men who adopt the ‘gender identity’ of being female or being women in any respect. The idea of ‘gender identity’ disappears biology and all the experiences that those with female biology have of being reared in a caste system based on sex.
Additional quotations from Gender Hurts:
https://www.goodreads.com/work/quotes/19344895-gender-hurts-a-feminist-analysis-of-the-politics-of-transgenderism