Yeah, exactly this. Hadn't it been for this forum I would have never pushed to get a whole range of bloodwork done, or a scalp biopsy since 2 derms I visited didn't recommend it. I would have never come across Donovan Hair Clinic and the amazing advice the founder (a PhD with experience at Mount Sinai, a professor at British Columbia etc.) gives. My first derm was clueless, told me I had thin hair, my second derm didn't prescribe any blood test or scalp biospy and just offered PRP, which seemed predatory given how expensive each session is.
The one I have now did a scalp biopsy but because I asked for it and I did all the blood work on my own initiative. I am working now with an endocrinologist as well for other issues but also related to hair loss but my journey has been a long one and it took a very multidimensional approach: supplements, hormones, spironolactone, minoxidil, changing my entire healthcare regime etc. I was diagnosed with AGA (from a scalp biopsy) and TE.
Researching, asking others for their experiences and comparing their personal experiences and their doctors' advice with mine helps a lot.
I know this sub and a lot of reddit subs in general tend to glorify doctors but they are not infallible and in fact medicine as a field has been even violent in many cases in history.
Believe it or not a lot of derms and even doctors in general can be horrible, this is not an individualized problem, a lot of doctors work as gatekeepers to medical resources, private derms often offer to do more expensive stuff not covered by insurance without giving you a lot of info on side effects or directions. And this is not even derms, this is the entire medical field, thank God I skipped the GP altogether because he was just delaying my diagnosis. There's even peer reviewed papers about the negative impact of GPs in life expectancy of cancer patients (for ex, one of them https://www.bmj.com/content/350/bmj.h2926), but I digress). This is why researching by yourself and "shopping for doctors" is important.
Side note but related, bc "derms are experts": Btw I had the same issue with eczema, they kept prescribing steroids for it even when I developed topical steroid withdrawal, which looks like this and is extremely painful: https://inews.co.uk/inews-lifestyle/living-tsw-acid-burning-through-skin-1653518
I found the root cause myself through the internet and literally reddit, and this is the case for a LOT of other people, see from this BBC article, the doctors mistakingly thought it was eczema, again a very very common situation: https://www.bbc.com/news/uk-england-kent-61083170.
Unless we have more studies assessing doctors ppl will still continue to view doctors or scientists in an overly simplistic dichotomous way and the feedback mechanisms to the fields will continue to be lacking.)