The vast majority of research on autism does not include Autistic people in the design or implementation. Therefore the voice, experience, and expertise of Autistic people are also not a part of the conclusions that are made about autism or the way it is defined.
"The autistic community advocates for autism research that is accessible, inclusive of autistic participation and perspectives, reflective of the priorities of the autistic community, of high quality, and written in such a way that it does not contribute to the stigmatization of Autistic people. Although there has been progress on these fronts, some of the language used to describe autism and Autistic people within published research continues to increase marginalization." https://www.liebertpub.com/doi/10.1089/aut.2020.0014