This feels like a silly over emphasis on a naming that ignores how alike it is to so many things that came before. Don't even have to go too far back to get stories of people finding themselves in a fantasy world through a wardrobe.

How many stories were about hidden worlds below our own? Isn't even that much different from "turtles all the way." Heck, even the Minecraft movie played with a literal mine going into a magical world.