I agree with what you're saying to some extent, that there are lots of people "identifying into" ASD, Tourette's, and also ADHD and a few other things.
However, I think they differ from some other conditions in that while you can actually to some extent "think yourself into" psychological difficulties like disordered eating, body hatred, low mood, anxiety, gender discomfort, self harm, functional tics, and various other psychological problems which may or may not reach a diagnostic threshold for a mental disorder, you can only either be right or wrong about having neurological or neurodevelopmental disorders like ASD or Tourette's (disregarding controversies about diagnostic thresholds and categorisation) — you can't think yourself into having them.
That makes the issue slightly less complex for ASD and Tourette's — you only need to look at the stringency, thoroughness and accuracy of diagnostic services, make sure they are capable of distinguishing genuine neurological or neurodevelopmental cases from those where something else (psychological or social) is going on instead, and talk about whether thresholds should be made higher or lower or kept the same. Whereas with things which you can, to some extent, "think yourself into", it gets more difficult to distinguish between cases on the basis of etiology, and may not be as important as distinguishing between, say, Tourette's and functional tics, where the treatment should be quite different.