"Again, you rwelcome to your beliefs, but what evidence are you offering up to support your beliefs. "
Observation, comparison and a long life - Non too scientific. I put this to you; How did society manage before the availability of diagnosis & treatment of kids who were perhaps a bit naughty/short attention span? Your answer may be badly, however I would suggest that the majority of "suffers" learned to manage their "symptoms" and went on to make their place in society. Regrettably a few ended up in asylums/jail. Asylums are now out of fashion, the habitants are on the street and the jails are now a flourishing industry in their own right such is our success with social/individual behaviour engineering.
"......excessive screen time is not currrently thought to cause ADHD (but I have seen studies where it can exacerbate it"
It's not the actual screen time - it's the substitution of play/imagination/exercise/face to face social interaction/etc with an electronic device (screen time). The devices themselves are completely neutral (much like a gun)- it's the over & miss use, thats the problem.
From time to time, I used to pass through a large housing estate, not far from where I live. Not a child/youth to be seen on weekend/holidays. One day we had an area wide, day long, electricity failure - kids everywhere, playing talking to each other, no doubt getting up to mischief - doing what kids should do. I had no idea so many young people lived in that community, until the "blackout". Power back on - no kids.
History is littered with medical trends/fashion. Most have some basis in fact/need/efficacy - for a few. In time, the enthusiasm dies down, a more rational/measured approach takes over and we move on to the next wonder drug/therapy.😈