The fear of penised women is one of the major drives that keep patriarchy alive.
By "penised" I mean not necessarily a physical organ, but something more abstract - the Freudo-Lacanian phallus, the symbol of power, privilege and dominance.
Salome, Judith, Yael/Jael and Jezebel were portrayed as beautiful and attractive women, who held power, had weapons (phallic symbolism) and were dangerous to men because of that. Throughout history men hated (and still do) when women hold "phallic" attributes - power, strength, knowledge, weaponry, sexually active role, etc. Sapphics, emancipated women, women who demand rights, women who hold power, childless and unmarried women, etc are and have been seen as a threat to the status quo regardless of what they do because they don't fit into the gendered division of labor where women do house chores, pacify men with sex (but receive no pleasure from sex because it's coded as phallic and thus inappropriate for women (see oppositional sexism)) and bring more future soldiers, workers and tax payers babies into the world. So when women have the means to avoid any of this, it's seen as the phallus (again, not the organ but the symbolic one) women cannot have.
Trans people, both women (mtf) and men (ftm), and other queer people destabilize this system of labor by opting out of it, which is why they're labeled as "queer" (= weird). There are women/people perceived as women who don't do the feminine labor and there are men/people perceived as men who do the feminine labor, but most of the attention is on trans women. Why?
Because they're the very penised women patriarchy fears, now literally penised. It's modern Salome, Judith, Yael and Jezebel who lure men but don't offer any component of the feminine labor, be it domestic chores, pacification through sex or reproduction, thus they're treated as a threat to men. That's why men feel "tricked" and "trapped" by trans women (just to mention, I think infertile and/or child free cis women are treated in a pretty similar but maybe rather condescending than hostile way). Obviously, unless patriarchy is dear to your heart, transfemininity is benign, just like female celibacy, homosexuality, or lack of children.
While I genuinely support queer people who just want to live an ordinary live in a suburban house with 2.5 kids and a dog (honestly, I'm not as radical in my personal life as you might think), assimilation is not the answer. The Other must not be shunned away, destroyed or defanged, but accepted as it is.
So, that's why I believe that queer activism and feminism must be the same thing: not just allies, but indistinguishable. There's no liberation for women if queer people are feared and queer people cannot thrive in misogyny.
Inspiration: Anti-Oedipus by Deleuze and Guattari, Male Fantasies by Klaus Theweleit, very superficial understanding of Julia Serano (I'm yet to read her book!) and even more superficial understanding of Shulamith Firestone, socialist feminism learned from Donna Haraway & her cyberfeminism, George Bataille, Simone de Beauvoir & Sartre, No Future by Lee Edelman.
