You might find it helpful to read Diagnosing Autism, Part 1.
The current diagnostic criteria for autism suck for a bunch of reasons. Here are a few.
Even with its many revisions, the DSM V - TR still defines autism only as a set of deficits. Social deficits, communication deficits, behavioral deficits. It's all about what's wrong.
The problem with this view is that autism penetrates to the core of the person. Autistic people weren't people before we had autism. Our autistic traits are a large portion of our identity. There is nothing about us that is not autistic. But to be autistic literally means we are a list of deficits without positive attributes, at least according to the DSM.
Many of the deficits described by the DSM V are also socially one-sided. Deficits in reciprocity, deficient nonverbal communication, and poor relationship quality. All of these are a nice way of saying that autistic people make 'normal' people uncomfortable. Because autistic people don't naturally give neurotypical people the emotional feedback they want, autistic people must be deficient, right?
The social diagnostic criteria make autistic people responsible for the feelings and validation of neurotypical people. Even the criteria describing restrictive patterns have tones of neurotypical validation. The inflexibility described is really a description of an autistic person as an inconvenience to those around them. If the relationship between the neurotypical and autistic person was balanced, these qualities would be a simple disagreement in priorities. But because autistic people are "abnormal," their preferences for sameness are wrong, and the neurotypical desire to shake things up is the right way to be.
Whoever wrote the DSM V criteria for autism are a nosy bunch. They're very interested in what others do on their own time. Whether it's stimming, special interests, or engrained habits, the diagnostic criteria for autism pathologizes how people spend their free time. The notion that others may do things differently than neurotypical people and be perfectly happy doing it likely never crossed their minds.
Unfortunately, autistic people are often unhappy. The world is hard on us. But if left to live our lives without the judgment of others, autistic people are as content with who we are as anyone can be. Robert Anton Wilson wrote "we have never seen a totally sane human being." We don't know what autistic people would be without neurotypical norms imposed upon them. And with diagnostic criteria as they are today, we're not going to find out any time soon.