Yes, umbrella terms like queer and transgender make perfect sense, but maybe not for the reasons many think.
You have probably heard the questions: “Being gay is about sexuality and being trans is about gender identity, so why do the two belong to the same queer community?"
Or: “Trans men and women suffer from gender dysphoria, while drag queens and ‘crossdressers"‘ are just ‘performing’,” so why should being trans be a matter of gender expression instead of identity only?”
Setting the false premise of “all crossdressers are just performing” aside, these questions are based on a fundamental misunderstanding, namely that membership in the queer and trans communities need to be based on some kind of easy definable common “essence”.
In the case of “queer” some would argue that that would be sexual orientation, I suppose, and in the case of "transgender," gender identity or gender dysphoria.
I am not denying that there may be biological components to the development of queer and trans identities. In fact, I think it is hard to explain the existence of queer and trans people without such components, given the severe social conditioning found in societies where the cis/het (cisgender and heterosexual) ideal is the norm. Why would anyone chose to be queer or trans, given the kind of harassment we see?
Yet, I do not think we – or science – have come to a point where such factors can be used to define social groups. Moreover, such litmus tests, if possible, would without doubt be used to invalidate some trans people, which is not a good thing.
In spite of this lack of reliable "DNA tests" for transness and queerness the existing LGBTQ+ and transgender communities represent meaningful alliances. Broad terms like queer and trans make sense at the moment we move from some kind of "objective" idea of what people essentially are over to the social scene.