Do you really need a citation that a non-verbal, uncommunicative and non-independent "non-functional" traditional autism case is different from what would often be referred to as "Asperger's", which is common amongst software developers? Or take people like Elon Musk, Bill Gross and David Byrne, who all claim to have Asperger's, Bill and David having been formally diagnosed. These people, who achieved great success, and went through most of their lives without needing a diagnosis, are clearly nothing like the non-functional patients with clearer traditional cases of autism.

Mostly anecdotal, my school psychologist back in the day sure believed it, and this would vary from place to place. She was a champion of "You give children the diagnosis that gives them the services they need". Autism being the one which gave children the services they needed, and she often expressed frustration at not being able to get such a diagnosis.

In general Aspergers basically meant no verbal delays, where Autism meant verbal delay. Autism was also around longer as a diagnosis. In general, I think theres a reason they changed the name of Aspergers to Autism and not the other way around.

It can be helpful to get a diagnosis of autism for kids in public school. Kids end up needing additional one on one time and resources are limited. Those with the biggest problems are the first to be approved for these resources, and a formal diagnosis makes it easier to get that approval.

This isn't really providing any clarity to the question, since you're simply restating your previous claim. How is a diagnosis of autism any more reliable?