My guess would be that when I was young the defining lines of what Mental Illness was ...was different. There were probably not as many options and certainly the diagnosis PTSD wasn't around. So my guess would be that many were diagnosed with Anxiety, Depression and such. Maybe soon the DSM will recognize CPTSD as diagnosis on it's own merit, instead of a sub symptom of PTSD.
I would hate to be a T trying to figure out a treatment plan for CPTSD. It is very complex for the patient and for the T as well I expect. There are so many types of trauma and I doubt one blanket therapy covers them all. It would be easier if it were only one trauma no doubt.