I think this is all utterly misunderstood. IMO autism is a predictive processing failure: the brain gives too much weight to inputs and inference and not enough to prior knowledge. This causes hypersensitivity to everything surprising, which is deeply unpleasant. The coping mechanisms are to try to shut out anything that's insufficiently predictable, to try to force things to be as predictable as possible, or to restrict attention to controllable and predictable things.
Regarding the fundamental mechanisms. This is the view that I subscribe to as well.
It explains "stimming". Repetitive behavior is soothing because its predictable. And it explains things like toe walking - feet are sensitive, and the inability to predict the stimulus of things we might step on is uncomfortable. Folks with autism may have a heightened discomfort with unpredictable sensations.
There is growing evidence that atypical dendrite development in childhood and early adulthood is linked to autism, schizophrenia and epilepsy.
I see autism and schizophrenia on a spectrum of predictive processing failure. Normal folks typically cannot tickle themselves. But folks with schizophrenia can - probably because its difficult for them to predict their internal sensations.
