When I was young in the 60s and 70s, autism didn't exist. Instead, if you couldn't function well enough, you were tossed in the special ed. bucket as "mentally retarded, unknown cause." If you could function well enough, you were just written off as a nerd or a geek. Nothing to diagnose.
Autism as a diagnosis became a "thing" in the 80s. If you aren't looking for it, you don't find it. Almost fashionable nowadays. For practical purposes, it didn't exist prior to then.
Another factor is that psychological professionals actually started seeing kids to diagnose them. I never saw a mental health professional my entire childhood. Most kids did not back then. My high school counselor wouldn't know what Asperger's even was, let alone how to identify it. Everything was ascribed to bad life decisions and moral turpitude.
In California at least, mildly autistic people who would never have been diagnosed started clumping together in Silicone Valley and other high-tech centers. Women with mild autism were finally able to get degrees in tech fields and work in the industry. They married and produced offspring with genes from both sides of the family. Prior to the rise of Big Tech, mildly autistic people were much less likely to meet and marry.
Psychologists started realizing there are just a many autistic women as men. Very recently it was believed that women could not be autistic. You still see shrinks that think that way.
It isn't a "crisis." We are finally seeing what the underlying reality was all along.