I see this as more of a metafictional reflection on heroic hunter/explorer fiction (e.g. Haggard's Alan Quartermain novels, or Conan Doyle's Professor Challenger books) giving way first to the occult-powered heroes of the pulps (The Shadow) and earliest comics (Doctor Occult, Zatara) and finally to super-powered characters. Once you had characters who could "cloud men's minds" or better, toss cars around and bounce bullets off their chests, somehow a hero who was "merely" brave, intelligent and handy with guns didn't do it for many readers anymore.