FWIW I don’t think the same about autism and OCD (at least not to the same extent). There are some similar problems with the soft diagnosis, but there is more going on there imo.
They both do have problems with variableness (particularly autism), but it’s more distinct from the general public.
My "personal hypothesis" is that the ADHD/Autism/OCD are fundamentally related somehow. The comorbidity between them is much higher than general population incidence, there's large symptom overlap, on a personal level I've found that I relate to and get on along much better with people who have at least one of those conditions, and a good 2/3rds of the people I consider close friends do.
They both do have problems with variableness (particularly autism), but it’s more distinct from the general public.