A huge piece of a physician's medical training is knowing what questions to ask (as well as how and when to ask) to uncover the sneaky things that aren't apparent on the surface. For example, as a 4th year medical student, I had a patient in the ER that came in with shortness of breath, fatigue, and chest discomfort. There were a couple hints of red flags, so I asked more questions that didn't seem like they were related at all. Was he having unintended weight changes, night sweats, or changes to his bowel movements? The answer to all three was "yes", but he had no idea why I was asking about that when he was there for breathing problems. I had a suspicion that he was having complications from metastatic cancer, and I was right. The resident I was working with hadn't even thought to dig into those other niggling suspicions and was more focused on cardiac and pulmonary causes of chest pain and breathing problems.
I can almost guarantee that a nurse practitioner wouldn't have asked those questions either. I keyed into some very subtle signs on his exam which prompted me to dig deeper, but NP's aren't even really trained on how to get a deeper history, let alone when to do so.
I am very glad that you were able to get your own care and didn't have any bad outcomes. On the other hand, I've had cis-female patients go to naturopaths or chiropractors to get estrogen and/or testosterone pellets for peri-menopause symptoms and they had no idea what the risks were. In the emergency department, I've had cis-female patients on estrogen replacement therapy that was not well managed show up with DVTs. Cis-male patients on supraphysiologic testosterone are at risk for several different kinds of organ failure along with a drastically increased risk of heart attacks.
I don't think that trans patients are terribly likely to harm themselves with DIY HRT, but having hormones available OTC is going to lead to a lot of cis people getting sick or getting killed by taking extra hormones to try to fix their problems because scammers and quacks have convinced them that hormones will magically fix all of their problems.