its not nonsense, its a well documented part of trans discrimination. trans people are commonly treated as if they are cis, and many doctors just don't have the kind of awareness of HRT's effects that you seem to think is commonplace. like, more than half of trans people have experienced medical discrimination. trans people are routinely confronted with medical professionals that refuse to acknowledge their medical histories. trans people have quantifiably worse physical health outcomes even when they do get care. i have not met a single trans person who hasn't experienced at least some kind of barrier to care. doctors refusing to perform mammograms, doctors who haven't even heard of HRT, doctors turning trans people away at emergency rooms. there is tons of data out there about this problem that you're refusing to believe even exists.

Competently treating trans patients is more than knowing what medications someone is on. I know trans people that have had doctors strongly push medical detransition for having minor temporary health problems completely unrelated to their HRT. Immediately hitting the 'medically detransition' button every time one value goes out of range on one blood test isn't competent care. Google 'trans broken arm syndrome'. This stuff all has an effect on whether or not trans people seek care and how competent the care they receive is. If you set up in the minds of medical professionals that trans people are 'actually' their birth sex then you're setting trans people up for receiving bad care, period.