This isn't internally coherent—if men are understood as always and only masculine, then it doesn't matter if they "act masculine," because their actions are inherently masculine, regardless of their content.
Essentialists accept that men can act feminine, one just can't understand their behavior in essentialist terms. For essentialists, people who defy gender conventions still exist, but when the essentialist witnesses them he doesn't know what he's seeing. I don't think any essentialist would say that it's literally impossible, on an ontological level, for men to act any way other than masculine. An essentialist would just say that male femininity makes no sense.
I don't understand how you square "the community accepting certain qualities as feminine" is what creates gender with your straightforward assertion that "feminine" has a simple meaning that is Lacanian and that nobody else here will agree with. Isn't it clear that the community is not accepting this quality as feminine?
When I discuss femininity, I mean feminine culture, not the literal qualities that define a woman. With this in mind, it's fair to say we should just talk about phallic and non-phallic qualities rather than masculine and femininity qualities. My mistake for not clarifying this earlier.
Phallic culture dominates pretty much all communities, whether they accept it or not. Name one community in which phallic and non-phallic culture is equally represented. Name one community in which non-phallic culture is better represented than phallic culture. The phallus is not a gender quality. It is a system of representation. And on this system, everything non-phallic is marginalized. Truly non-phallic women are not recognized by society. Women are expected to always serve male desires. In this way, most women are phallic. Can you even name a women in mainstream culture who doesn't cater to the male gaze? The point I'm trying to make is that there is a second representation-system alternative to the phallus, a second system that does more to help women. In short, the feminine (or if you prefer, non-phallic) experience is not well-represented in our mainstream culture, and I want to change that, so we can approach gender-equal representation. Do you really want to deny that feminine, non-phallic culture exists and is underrepresented? If there is no feminine culture, how do we even do feminism?