...It's a children's fantasy series.
This is a terrible dismissal of a GACHA employed by people who have no counter claim or actual reason to favor A over B.
The Lion King is a children's fantasy, but we, the audience, still know that Mufasa isn't going to sprout wings like a griffin and fly away from the stampede, or that Timon is going to usurp the crown and become king of the Pride Lands. "But these things could totally happen in a cartoon about talking animals!"
But they don't. It's because fantastical or grounded, a literary work, be it a film, novel, game or series is weighted by the shackles of It's OWN LOGIC. There absolutely NEEDS to be a rule book that is adhered to in order to make stakes that the audience cares about, in order to make compelling characters whose success or failure resonates, and, especially in fantasy, to ground events and make those fantastical, whimsical elements more pronounced in the work.
If anything could go without a second guess in fiction, solely because it's fiction, would the audience care when Neo learned how to manipulate the code in the Matrix? Would the audience feel intimidated by Sephiroth impaling the Midgar Zolom on a tree? No, because there's no need for internal logic, rules, or stakes because it's not real deep.
As a last note, this "it's a children's fantasy," thing is used on the stupidest properties. I see it used here, and on Star Wars. Find me a ten year old who is on the edge of their seat and fully understands the gravity and pathos at play during the senate meetings on Coruscant where they debate (in a committee!) the taxation of trade routes to outlying star systems. Find me a ten year old who really resonates with Aragorn's struggle as the fated king of men, always afraid that he possesses the same weakness of avarice as his forefather. Fuck, Find me a ten year old who can make it past the Tom Bombadil chapter in FotR.
I'll never stop shaking my head at people who think if it has aliens or elves or blasters or swords for the kiddos. High Fantasy is traditionally a genre that would scar children, should they possess the miracle in this day and age of being literate beyond Doja Cat lyrics.
Tolkien's works have always been honest, and above all else, united and singularly focused on the perspective and life experiences of one artist. This is one man's life work, and it should be preserved and passed on for what it is and was, not what other people with far less talent or life experience deem it SHOULD be or is missing.