Yaarel
🇮🇱 🇺🇦 He-Mage
It seems to me, most D&D players today in year 2023 have never heard of most of authors in Appendix N.I think most of the time when people fail to use DND for things other than straight Appendix N, its not so much that the game can't support it but more that they're failing to properly mix the genres.
The N books that they might have heard about are: Tolkien, Conan, Cthulhu, and Tarzan. Maybe, John Carter.
I happen know and like Andre Norton and Michael Moorcock (picked them up cold from a library scifi section), but I doubt most D&D players have heard of them.
Meanwhile the scifi that D&D players today do love and care about are absent from Appendix N.
Appendix N is less relevant in our century today.