Oh, I didn't think you were being cavalier about diagnosis and that part of my comment wasn't directed at you, but was an aside/explanation for why I felt it mattered I hadn't been told by a professional.

I of course think we should just be generally helpful and kind to people and their quirks and preferences. Just part of keeping society friendly and welcoming.

I just prefer if people distinguish between feeling a certain way and being externally evaluated.
Before I actually got a diagnosis I preferred not to say I had ADHD. I had difficulty focusing, I tended to get distracted, and all the management strategies helped me a lot, but that was subjective.
Likewise, a family member has an actual gluten allergy. The people who prefer not to eat gluten but can have made it a lot harder for her because the line is blurry.

It's purely a belief that accurate reporting and assessments make it easier for everyone, not that we should dismiss one and not the other. Doing that is what made people blur the line in the first place.