I doubt that this is true.
Firstly, it’s often very presumptuous to assume that a particular historical development would never have happened if one particular person or group hadn’t done it.
Also, it seems to me that the development of increasingly sophisticated effects technology would likely have been a natural boost for superhero films, even in the absence of Superman. I think it’s just as plausible to argue that a key reason for the B-movie status of superhero films was due, at least in part, precisely to the fact that it’s hard to make superheroes do their stuff without lots of money and/or visual effects. It seems like a genre that was, in some ways, waiting for technology to catch up with imagination and ambition.
Come on, you know better than to make this sort of appeal to the masses in a thread about movies.
In a thread called “Movies you hate but everyone else seems to love,” you listed Saving Private Ryan, Titanic, and The Sixth Sense, and said:
Of course, when it comes to these three directors, the overwhelming majority of the planet says you’re wrong. Very, very wrong. If your opinion was a superhero, it would be Captain Wrong. 