Fantasy literature (more widely, The Fantastic, which includes science fiction, horror - Frank and Drac, fables and whatnot) has developed in a similar fashion as pop / rock music.
I have an interesting book calling itself a "picture book", which is just a huge collection of interesting and / or trivial information shown visually.
It's the German translation of a 2009 book by David McCandless, original title "Information is beautiful".
It has a two-page spread detailing (or trying to) developments from the 1960s to the 2000s in pop / rock, with cross influences.
Talk about a spaghetti plate!!! I have never even
heard of at least 90% of the styles mentioned, and have no idea about what some of the remaining 10% sound like.
But they all have their following, apparently. Some may have petered out, or evolved. And with revivals cropping up at intervals ...
So too do the various variants of Fantasy / The Fantastic have their following. Or other genres which make me roll my eyes where some
authors have had some massive sales.
Some German "literati" types might, for example, turn up their noses at some guy from Stratford-upon-Avon who never managed to write a "Faust" and was basically just a playwright who dabbled a bit in poetry. And a lot of what he wrote he stole from Italian authors, and don't get me started on the accuracy of his historical stuff.
Let the free-for-all rumble begin!