This is not understood by the younger people. The old seamless basketballs that were leather were not easy to handle or shoot. Posters are always comparing modern shooters to people that were shooting a much different ball.One thing to note, while dunking in games was apparently not done much (if at all) in the early half of the 20th century, that doesn’t mean it wasn’t done outside of games.
I don’t remember exactly where I read this but reportedly players were dunking (or at least trying to dunk) from the very first times goals were hung around the turn of the century. Of course basketballs were bigger than they are today so it would have been more difficult.