Look, I get it and somewhat agree. However, the reason for the diagnosis (and any diagnosis) is treatment.
Maybe there are two different conditions that require speech, occupational, and behavior therapy to different degrees, however, in terms of convincing insurance companies in the US to cover those having a single diagnosis makes everything easier.
It's not as if a separate diagnosis would change how a speech therapist interacts with a child.
I applaud efforts to figure out what is going on and to categorize. But I also think that practically the ragbag diagnosis makes treatment a lot easier to access for patients.