I'm autistic which is also a disorder. Like ADHD it's a neurodevelopmental disorder because from a scientific and medical POV the brain developed abnormally compared to a neurotypical person's brain.

I guess your point is why does it require a label at all but science abhors a taxonomic vacuum, everything must be classified and if so I'd rather it be a disorder than a disease or illness.

Of course this opinion is just mine, I have no idea how other autistic or adhd people see this as I don't keep up with the neurodiverse community and what words are considered good or bad.