One theme in our societal decay is the loss of focus on reality. A concrete example of this is the trajectory both fantasy and science fiction underwent during the 20th/21st century:
Philology -> Tolkien -> Dungeons and Dragons -> Queer dungeons and dragons/glowfic/etc
Industrial/Science books for children -> Heinlein -> Star Trek -> Queer Space Opera/glowfic/etc
You end up with the same mush in both cases, but with slightly different aesthetics.