As someone who actually has an ASD diagnosis, and also has kids with that diagnosis too, this kind of talk irritates me…
If someone has a clinical diagnosis of ASD, they have a psychiatric diagnosis per the DSM/ICD. If you meet the criteria of the “Diagnostic and Statistical Manual of Mental Disorders”, surely by that definition you have a “mental disorder”… if you meet the criteria of the “International Classification of Diseases”, surely by that definition you have a “disease”
Is that an “illness”? Well, I live in the state of NSW, Australia, and our jurisdiction has a legal definition of “mental illness” (Mental Health Act 2007 section 4):
"mental illness" means a condition that seriously impairs, either temporarily or permanently, the mental functioning of a person and is characterised by the presence in the person of any one or more of the following symptoms-- (a) delusions, (b) hallucinations, (c) serious disorder of thought form, (d) a severe disturbance of mood, (e) sustained or repeated irrational behaviour indicating the presence of any one or more of the symptoms referred to in paragraphs (a)-(d).
So by that definition most people with a mild or moderate “mental illness” don’t actually have a “mental illness” at all. But I guess this is my point-this isn’t a question of facts, just of how you choose to define words.