LGBTQ+

Gonna have to disagree here. The social aspect of it all is just as important of the medical aspect. While there are trans issues that are mostly medical in nature, there are equally trans issues that are more social in nature.

I'm not sure what contexts you've seen truscum being used in, but from what I know it's a term used for people who insist on a medical diagnosis in order to be trans. The problem with this, imo, is twofold. There's a long history of medical gatekeeping that enforced cisheteronormativity in order to get a diagnosis of gender dysphoria, leaving out all other forms of self-identity (among a whole host of philosophical issues). And the second is just the lack of understanding and research of the broader medical community. Treatment guidelines are all over the place, often misguided, and usually inadequate to achieve the goals of the patient.

Truscum rhetoric often reinforces cisheteronormativity which is mostly antithetical to what being trans is about in the first place. That's not to say that the trans community doesn't struggle with medical diagnoses or that that's not important, but to use a diagnosis as the benchmark of what being trans is, is usually needlessly exclusionary.