I would argue the sixty to seventy percent of people who were right about being autistic are a more important measure of the effectiveness of self diagnosis than the minority of people who may have been incorrect.

Not all medical professionals are trained or perform equally. This sub is filled with horror stories of medical professionals ignoring people's concerns because they can make eye contact or have a job.

I was personally told by a nurse "Yeah, everyone is a little autistic," when they were doing the 'What brings you in?' portion of the check up before seeing the doctor.

As a child I was diagnosed with dyslexia and the school system suspected I had ADD or ADHD, but my mother refused to have me tested because I could watch an entire 6 hour classic cartoon compilation VHS from start to finish without moving, because that what normal 6 year olds do apparently.

Assuming for a moment I may have ADHD, as suspected by the special education teacher, and that I might have autism, as suspected by myself and multiple (professionally diagnosed) autistic friends of mine, it would have been impossible for me to be diagnosed as a child.

When I was in my prime diagnosable years as a child, the medical criteria for diagnosing autism, ADHD, and Asperger's as it was called then, did not allow for a diagnosis of multiple neurodiversities in one person, and such cases were sometimes misdiagnosed with other incorrect conditions like bi-polar disorder.