There are standard batteries of tests now. I'd be surprised if they were completely unknown. The need for evidence back into childhood does probably remain, but I think most pros who understand ADHD know that grades are only one possible indicator.

That's especially true for gifted people (guessing from your "sounding like a dick" sentence), where "twice exceptionality" can be tough to recognize due to smarter people being able to find better coping mechanisms. That particular issue is not unique to ADHD, comes up with dyslexia and other learning difficulties too.