A very good description.
WWII vets sometimes, but not always, had a period of rest after the battles that they were in. Battles with an identifiable enemy and usually a front line of some sort. Those who were involved in continuous fighting were candidates for battle fatigue, the old name for PTSD.
The pace of fighting in Vietnam was often much higher with troops being ferried from one fire fight to the next. No real front line, and an enemy who would meld into the local population. And courtesy of Lyndon Johnson and Robert McNamara no plan to win, just fighting with no foreseeable end.
Yup.