Rmaddy, I think this is a very interesting debate. Things should not be oversimplified in black or white. Here are a few additional comments from my experience.
1. Yes I got an official GD dysphoria diagnosis made by a well known gender therapist, Anne Vitale (author of a great book, the Gendered Self), she wrote that her diagnosis is based on my reaction on (I quote her) "anti- androgens and cross-sex hormones. It is well known that Gender Dysphoric males taking anti-androgens and cross- sex hormones experience relieve from distress and anxiety confirming the diagnoses. This differs markedly from cisgender males placed on a similar regimen to counter-act an enlarged prostate, find the experience unwelcome and react with newly acquired agitation and restless anxiety."
2. Yes you can still be depressed with HRT, but if you can stand to have your testosterone levels divided by 30 and feel better about it, it confirms the diagnosis.
3. It makes sense to start with a psychological diagnosis before starting HRT, but confirmation by HRT can then happen.