I have to be honest, I just don't get where the over-diagnosis idea comes from, and I think it is a myth. "Labelling" by people not qualified to diagnose may well be more common, but not formal diagnosis of the kind that I would hope the statistics are measuring.
The experience of most people I have spoken to, whether autistic adult or parent, is that it is often difficult for many to even to obtain an evaluation (which would lead to under-diagnosis). By definition, a patient's traits have to be "problematic" for a diagnosis to be considered, and the diagnostic manuals have always been very clear on this point. "Sort of behaving like" is not going to get anyone a formal DX in all but a tiny minority of cases where the doctor is straight up crooked.
In terms of parents, my experience is that most of them are scared to death that their child might be diagnosed as autistic, and I have yet to come across even one parent who is desperate for a diagnosis in order to explain some normal childhood expression of personality. Again, I think this is a myth stemming from the media selectively choosing their anecdotes to suit their narrative.
I really fail to see why people think there is any mystery to be solved (other than belief in the bovine excrement spouted by the mass media). The criteria for diagnosis have been widened, a couple of generations of older people are being diagnosed because they never had the opportunity before, and many nations have expanded access to diagnostic evaluations. I don't see that there is any need of paranoid explanations, as there is absolutely nothing out of the ordinary that needs explaining.
_________________
When you are fighting an invisible monster, first throw a bucket of paint over it.