To those arguing for reclassification or separation of diagnosis, my question is this: where do you draw the line?
The main reason why the separation between "Asperger's" and "classic autism" was dissolved was that for many people, which diagnosis you received depended on the day, the diagnostician, and the environment in which you were assessed. I never neatly fit into a category, and I'd say the majority of other autistic people I know are the same; somewhere between the two.
If they're considered separate conditions, how is it possible that many people fit the criteria for one condition one day and another condition the next? Or have one as a child and another as an adolescent, and perhaps even another as an adult? I was diagnosed in my teens after my mother's concerns were dismissed in my early childhood, and I was diagnosed as having what would have been called "Asperger's" even just a year earlier.
As a young child, I think that label was an adequate, if somewhat lacking, diagnosis for my particular issues. I'm verbal, I liked school, I had a small group of close friends. By my late teens, however, it failed to capture the fact that I will never live independently, still need assistance with hygiene and toileting when I'm even mildly ill, have self-injurious meltdowns, and shutdowns where I lose my ability to communicate. If someone saw me in those not-infrequent moments, they'd assume I was a closer, if still inaccurate, fit for "classic autism."
Realistically, unless there are dozens of subcategories created and it's established that people can move between many of those categories over the course of their life, most autistic people will fail to fit into smaller, more rigid criteria. And at that point, the categorisation is effectively the same as just describing each person's needs and symptoms, as we tend to do now, and less helpful for establishing support needs to boot.