The early CT70s had the automatic clutch only, as did some other small Hondas, Trail 90 CT90, Step thru CM91, step thru 50. I'm sure they were trying to keep it as easy as possible for the beginning rider. Later, they offered the CT70 with either auto or manual clutch. I think the auto clutch was more popular.
My generous boss at the Honda shop GAVE me one, for a season, if I would just ride it at the local minibike races. It fit in the backseat of my Mom's small car with the bars folded down. I was a lousy rider, but the bike was clearly superior, and we sold all we could get.