Umbrella terms like "queer" and "trans" are implicitly defined by the way the dominant cis/het culture behaves
There is a follow up article on the umbrella interpretations of the terms “transgender” and “queer” over at Crossdreamers.
The main point is that it is hard or even impossible to define the groups of queer and trans people on the basis of some inborn “essence” that makes them what and who they are.
This does not mean necessarily that there are no biological components to the development of queer sexualities and identities. Given the intense cultural conditioning against queer lives, it is hard to understand how anyone would become “rainbow rebels” without some kind of non-cultural factors.
Still: We know far too little about the complex interplay of possible genetic, hormonal, epigenetic, social, cultural and personal factors that makes queer people queer and trans people trans to use these models to determine who is in and who is out. Moreover, if we had such a model, I am pretty sure that one too would be used for social exclusion purposes, and we do not want that.
What all queer people have in common, though (and this applies to all letters in the LGBTQAI+++) is that we are being excluded and invalidated for violating the traditional binary narrative of pure man meeting pure woman and having pure cis/het kids.
This narrative does not distinguish clearly between gender expression and gender identity. which is why both gay, lesbian, bisexual and transgender people are seen as a threat to the ruling cultural belief system, a belief system that for many, puts gender roles at the center of the social order.
So broad umbrella terms like queer and trans makes sense, because these groups are not defined by some kind of inborn nature, but by a cultural setting that denies them the right to live their lives as they are.