I think it's simply a matter of social communication disorder not meeting the full autism-spectrum criteria for "restricted and repetitive behaviors and interests" (plus sensory processing problems). Not to say that they don't have or never had any of these things, just that they didn't have enough of them or they were too mild to register. There are several threads lying around regarding social communication disorder. Basically to get an SCD diagnosis you would have to have Asperger-like problems with social skills but not qualify for a full autism diagnosis. Not meeting the full autism criteria is written into the definition of SCD. A proper case of Asperger's, on the other hand, would meet the full diagnostic criteria for DSM-5 Autism Spectrum Disorder (there are also other threads lurking about regarding that), but be on the milder end.
_________________
Right planet, wrong country: possibly PLI as a child, Dxed ADD as a teen, naturalized citizen of neurotypicality as an adult