OK, so we start with the universe being infinite, and the following implication that anything that could possibly happen is actually happening somewhere out there in the inky black yonder. Our works of art are generated by some kind of connection between our world and other worlds. Not all of them (some people just write shitty stories or make crappy music or paint bullshit art, after all) but the art that is created from that place of pure inspiration that artists are lucky to tap into a handful of times in a lifetime – it can offer glimpses into these other worlds.
And maybe thinking of them existing in a far-flung corner of the universe is the wrong idea, maybe they’re right next door to us, and our worlds are all stacked on top of each other, or floating around and rubbing up against one another in different configurations, and that’s how you get trends in popular culture, they represent whatever split-dimension parallel world happens to be closest to us in the stack.
Somewhere out there is a world (or many worlds) populated by superheroes and supervillains, who read novels and comics about a mundane world where there are no powers and everyone is so oppressively equal. The variations spin off in endless iterations as we float around each other inside of some kind of nth-dimensional no-space. Grant Morrison is not a writer, he is a futuristic adventurer, pioneering the exploration of our dimensional neighbors and attempting to initiate first contact with whatever alter-verse can hear him shouting in the dark.