That WaPo article is fantastic and should almost be required reading for denizens of the Beauty Parlor.
Anyone who has worked in a pediatric behavioral setting knows exactly the kind of parents who will shop for a clinician until their kid gets an official diagnosis. Every clinic has parents who are desperate for a diagnosis. My own belief is that they overwhelmingly fall into two camps. The first group just want an explanation for their kid's issues that isn't "Dad was 55 when the child was conceived, Mom is a Cluster B dumpster fire, and all the hands-on, down and dirty childrearing has been done by a succession of overworked and underpaid au pairs". Most of them have been searching for years, watching their kid struggle with things that everyone else's children appear to grasp effortlessly. Even if "autism" isn't the real problem, they want the diagnosis because every other investigation, including genetic and neuropsych testing, has turned up nothing. There is obviously something wrong, but without an official diagnosis, any diagnosis, their kid doesn't qualify for an IEP and can't receive free therapeutic intervention through the school district. Autism feels like an answer, and that's all they want. Doesn't have to be the right answer, doesn't have to change anything about the daily struggle of raising a special needs child. Often, these are upper-middle class, older parents with professional degrees and a "comfortable" lifestyle, and they have the money to throw at private clinics. They don't care about getting free therapy, they just want their kid's problems to not be their fault. My own opinion is that this group accounts for the unusually high rates of autism diagnosis among children of older white parents.
The other group understands that a diagnosis is required for collecting SSI on their child's behalf. They may at least partially grasp that there's not actually anything wrong with their kid that isn't situational, but even if they do, they have issues themselves, including poverty and lack of education, that render them incapable of making the changes necessary to improve their lives. They will push and push and push for the diagnosis because it feels like their only option.
Additionally, the diagnostic criteria for many genetic and developmental disorders include "autistic features". Kids who would have just been diagnosed with "developmental delay" or "mental retardation" ten, twenty, or thirty years ago now receive an autism diagnosis. There are a lot of reasons for this but one of them is school Title I funding. I know there are people here with expertise in special education, so I won't even try to discuss it, but there's pressure to diagnose autism rather than developmental delay for financial reasons.
All of this is super disillusioning for behavioral researchers. Personally, I take issue with the first group more than the second.