They were more flexible back then... "comics" meant pictures and word balloons, not any one genre...today "comics" means (to most of the world) superheroes, period.
Well, to most of the USA, maybe, although manga is the dominant form of pictures and word balloons, with fantasy adventure, sci-fi, and romance being the dominant genres even in the U.S. Naruto, Fruits Basket, Yu-gi-oh, Bleach --these are the big "comics" these days, not 10th generation retreads of 1930s superheroes. If anything, comics publishers, with the exception of DC and Marvel, are more flexible than ever.
Wikipedia has good articles on Wertham and Crime Comics, as well as superheroes --their decline and fall.