Good thread on worldbuilding and why JK Rowling really isn't great at it. https://twitter.com/ellle_em/status/1353357327030771712

Though I think the comparison with Tolkien isn't really comparing like for like. HP is relatively "low" fantasy - the stories take place in the "real world", albeit a secret, sectioned-off part of it. Tolkien's legendarium, by contrast, is mythology. https://twitter.com/ellle_em/status/1353363215871324160

So we expect the magic and fantastical elements of Harry Potter to follow some sort of consistent rules and to have consequences, and thus it's jarring when they don't. LOTR doesn't need to follow such rules - it's fine for the magic to merely advance the narrative.

The basic framework behind Tolkien's whole fictional world is that Tolkien i) absolutely loved pagan mythology, but ii) was a devout Catholic. The whole Middle-earth mythology is an attempt to reconcile this - pagan myth stories within monotheistic & Xtian theology and themes.