@ember "if this makes you uncomfortable, try to figure out what part of people you actually want to talk about. if it turns out that you just want to talk about birth sex, that may be worth interogating."
I think this is a very underhanded and disingenuous rhetorical move. You're trying to imply there's something wrong with even implicitly acknowledging gender assigned at birth in some contexts, because it is relevant to what most of us mean when we talk about trans issues, trans people, and trans experience (or would you remove the vocabulary to discuss such things?), and creates unique and specific struggles and experiences that it is useful to have a word to talk about, with being some kind of bioessentialist or something that thinks someone's coerced sex is the only important thing about them. That's what it seems like you're trying to imply by going from "if you don't like the fact that I removed actually having a different AGAB than your gender identity from the idea of being trans" to "all you want to talk about is people's birth sex."
That's an utter crock of fucking shit. This definition is deeply problematic, and it does make me a bit concerned, but that's not because "ALL I want to talk about is people's birth sex." I don't have to think someone's AGAB is relevant whatsoever in most contexts, to think that in the specific context of discussing trans experience the fact that someone's AGAB was *different* than their actual gender is sometimes relevant. When we use the usual definition of transness, crucially, we aren't focusing on someone's AGAB itself, but their current gender and the fact that it is different than what they were assigned. That's why it's completely and utterly wrong to say that words like transmasc and transfem are just euphemisms for AGAB — you're leaving out all the most emphasized parts of them, the components that fucking make up the words for chrissake, to focus on something else, because you want to push your poorly thought through redefinition. Yes, the words implicitly acknowledge what someone's AGAB might be, but that's not the important part for the discussion, it's the fact that they overcame their AGAB to be who they are now.
Also, yes, people who overcome the social pressure to experience or express gender in one way in order to do that another way often share experiences with trans people, but there's still a difference between a cis person and a trans person in the context of our experiences of gender, and it's useful to have vocabulary to refer to that.
If you want to make "trans" just literally mean "gender nonconforming" then we'll have to invent a new word to mean "trans" and the cycle starts again. At bottom, I understand the inclination to try to remove all reference to AGAB from everything, but sometimes the fact is relevant to our lived experiences and histories.
And anyway, with these definitions they're still defined in terms of initial social control and imposition, so ultimately they have the same problem as the problem you had with the current definition of being trans. "If it turns out you just want to talk about what society thought people should express their gender like, that may be worth interrogating."
To completely eliminate that, you'd have to just make "transmasc" mean "masc" and "transfem" mean "fem," and again, to some of us, the fact that our AGAB was different from our gender is relevant sometimes, so we would still need a word for that so we could explain it.