It would depend on who's doing the labelling. I think I agree with you in that society doesn't need to label them as handicapped. However, I was thinking more

It would depend on who's doing the labelling. I think I agree with you in that society doesn't need to label them as handicapped. However, I was thinking more about people labelling themselves internally, which is what the linked article focuses on. In that case, thinking of one's self as handicapped can be beneficial, which is what the article presents example of. Since there is a medical professional involved in the diagnosis, they should be able to steer the patient towards the mindset that would be most beneficial for them, given each individual's circumstances. Repeated sessions work towards helping psychiatrists figure out, as you say, "which exact behaviours can be attributed to autism and which to personal development", and they can advise accordingly. Minor nitpick: you said "psychologists", when "psychiatrists" would be more accurate. The latter are medical professionals who have gone through at least 14 years of study and practice, including a residency at a hospital, and they are the ones who are able to diagnose and prescribe medications. They are doctors, in the full sense of that word. Psychologists are not medical professionals (but that doesn't mean they're not useful).