Medical transition isn't just "full" genital surgery. It can include puberty blockers, hormone therapy, electrolysis, vocal training, and other surgeries, such as top surgery or facial feminization surgery. Indeed, if you go to "Myth #4" of your Vox source, you would've seen that transitioning isn't a singular surgery.

Certainly healthcare is a very individualized thing and statistics alone can't predict how someone will react, but the consensus is that transitioning improves well-being and quality of life in multiple domains and that transition regret is extremely rare. As well, transition regret usually comes from lack of social support or poor surgical techniques.[1]

Transgender identity (a gender identity different from the one assigned at birth) isn't a medical condition, but gender dysphoria (distress over one's gender and assigned gender) in the DSM or gender incongruence in ICD (incongruence between one's gender and sex characteristics) is a recognized medical condition that usually improve with transitioning.

I have a unique anecdotal response to your point about the medical and social models of disability, as a transgender woman who does not want to cure her autism. Namely, hormones and legal transition affirmed my (transgender female) identity and has greatly improved my subjective well-being, giving me new forms of hope and happiness I had never before experienced, and the various antiautistic interventions I've received invalidated my (Autistic) identity and the effects of those interventions ranged from null to traumatizing. Unless you are arguing that medical care is inherently bad, you are comparing apples and oranges.

To go back to the original author, she is not advocating demedicalization, at least in the sense you are talking about. She is arguing that people should have access to medical transition even if it doesn't improve symptoms of gender dysphoria or even if it makes their symptoms worse. What she is truly advocating for is that the only criteria for gender-affirming surgery should be that the person wants it. While I do disagree with some of her statements, like that there are no good outcomes in transition, ultimately, I agree with the assertion that doctors shouldn't dictate their patient's bodies.