I used "spectrum" to mean that ADHD is not always severe enough to cause outright disability, but the underlying problems can still be present to a lower degree.
The parent mentioned "procrastinates or can struggle with focus without having ADHD" (emphasis mine) and I wanted to point out that some of those people may also have some very mild form of ADHD.
While, sure, everyone does have different specialties, they could also have some traces of ADHD that aren't severe enough to give them all the symptoms but still manage to hurt their performance in certain areas.
Also, I said nothing of autism. Please don't extrapolate
In reality, it means
"But doctor, how can you attach this very serious and stigmatizing diagnosis to my child while skipping half the tests in the official criteria and fudging the numbers to reach some threshold number?"
"Oh don't worry, it's a spectrum, you see"
...
"But doctor, what you just entered into my medical records is not what I told you at all, how can you be sure you're making the correct diagnosis if you're not really listening to what I'm saying, and when you're completely misrepresenting my situation?"
"Well, it's a spectrum you see"
For example, ADHD controls my life and I was never diagnosed with it until I figured out the symptoms myself, because nobody could ever see me struggling with it - there is no fighting it for me. However for some others, their ADHD is trivially controllable via medicine or habit-forming.
When analyzing people what is not a spectrum? Every human attribute can be placed on a spectrum. Even other diseases, disorders, etc.. A broken bone can be a hairline crack or shattered into pieces.
