what was like the 17th most compelling thing about the Harry Potter series (people being sorted into factions by personality type)
You say that but I also think it was Joannes best bit of world building (Along with getting a Hogwarts letter). It is the part with the most buy in from fans. Even people who have never read the book know what Hogwarts house they are in. If that is not immersive world building I don’t know what is.
You say that but then it’s if Sci-fi was good it would just be called literature