The autism spectrum was so named because various interested parties believed it would be more useful to treat it as a “spectrum disorder”. For instance, if a patient did not squarely fit into the autistic diagnosis, insurers would be more reluctant to fund treatment; schools would balk at the financial and logistical burden of accommodation, etc, etc.
Do “spectrum disorders” share important characteristics with other things that have been called “spectra”? Only in a superficial sense, and it would be counterproductive and even dangerous to resort to this sort of linguistic reasoning.
Autism isn’t a response curve.
