(....besides the tragic delusion that the increase was caused mainly by vaccines in some way or other....)
At many websites, in innumerable leaflets, in the "introduction" paragraphs that adorn almost all journal papers, and even in the book "Autism: The Facts" by Simon Baron-Cohen, the reader is liable to get misled by some of the statements. This is partly because some of these authors think it useful to provide a dumbed-down idiots' guide explanation for people who are supposedly too busy to spend a little more time learning a proper understanding.
Firstly, the myth that the human race can be divided into those who "have" autism and those who do not "have" autism. Or as they alternatively put it, those who are "on the spectrum" and those who are not. Or those who are autistic and those who are neurotypical. In reality there is no such distinction, it is merely the human races' obsession with sorting people into categories operating here. It is no more sensible to say that someone is "on the autistic spectrum" than it is to say that a person who is 6 ft 1 inch tall is therefore "on the biggism spectrum", or "has biggism". Rather we are all on this "spectrum" together to greater or lesser extent.
Secondly the myth that Aspergers is distinct from autism. This distinction arose merely because Kanner and Asperger simultaneously came up with these ideas in separate countries. Sixty years of research has since failed to establish any clear distinction but instead a huge amount of commonality.
(Review of Asperger's/Autism relationship by Tony Attwood.)
Thirdly the myth that autism is properly described in terms of a "triad of impairments". On the contrary a whole collection of characteristics of the autistic syndrome was long ago listed in the table of Wing 1976, which you can also find in my 1993 paper linked at the top here. When researchers can't explain some fact, they tend to prefer to just forget about it, and so this pseudic simplification took on a conveniently flattering life of its own.
Fourthly, if a person prefers to be alone, prefers reading a book to going to a party, and is lost for words on meeting a person they want to speak to, this does not mean they are even slightly autistic or Aspergeric. Rather they may be just be very introverted. And introversion is entirely different from and unrelated to autism etc.