Aren't you guys talking about an academic and somewhat theoretical definition of the term "spectrum"?
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"