I'm a little skeptical. I just watched the 5 episodes on Netflix of 'Masters of the Universe: Revolution' and there is NO WAY that Eternia makes the slightest bit of sense, it just doesn't. It is NOTHING but a stage for epic conflict. I mean, there's a 'kingdom' and 'citizens' and a 'man-at-arms' and whatever, but it's all just as real as any Broadway set, it's all symbolic at best. Nobody sat down and said "there's such and thus an economy and it can therefor support a palace of such-and-such a size" or whatever you'd need to do to imbue it with even slight realism. Heck, the castle is most of the size of the town, and this one town seems to be the WHOLE PLANET. It makes exactly enough sense for 8 year olds, basically.
Lets imagine an RPG setting, Paranoia. Nothing in Paranoia makes any sense either. I mean, some of it COULD, maybe, and I don't remember enough details, if they even existed, of the setting. Still, nothing like "why don't the clones all just run away?" is addressed, at all. It's all just a convenient fiction that serves the purpose of the game. AND IT WORKS. Doskvol is equally ridiculous. I mean, they claim the people eat fungus and plants that grow in the dark, but we all know that's impossible. Everyone would starve. Well 'magic' is of course the answer, but we have no knowledge of what that's capable of, or how it works, it is just some handwavium, and yet the setting WORKS.
I haven't watched any of the new MOTU, so I'm going off of the original series here, but I agree that there are some settings where the hows and whys are essentially changed up as the story progresses. Mortal Kombat is a notable example here, since even in the more recent multimedia entries into the franchise (which have had a tighter presentation than their earlier counterparts) seem to delight in changing things up on a massive scale every so often. And yet it remains entertaining.
The thing is that, in both of those examples, the setting doesn't so much "work" as it does "stay out of the way." Which is fine if you only care about a particular campaign world insofar as to how much it plays into what the characters are doing. And in my experience, there are plenty of TTRPG fans for whom that's their
raison d'etre; the world revolves around the PCs and their exploits, and so it only matters in terms of how exciting the players find it.
But that ignores all of the other players for whom that excitement comes from having a world that isn't just window-dressing.
Being able to explore how a world works, and interact with it on its own terms, has been a source of a lot of fun for myself and a lot of other players that I've known over the years. Sure, if all we wanted was "fight the advancing evil" (which basically summarizes MOTU, Mortal Kombat, and a lot of other franchises), particularly where how the PCs fight relies
entirely on their own powers and abilities, rather than needing to engage with powerful local forces (who are presumably dynamic characters who have their own vested interests, considerations, fears, and such, all of which are tied into aspects of the world they inhabit, rather than being static characters until the PCs interact with them), search for long-lost artifacts, recruit extraplanar/divine aid, carve out a power bloc of their own, etc., then yeah, the rest of the world doesn't really matter. You can be dungeons-delving murderhobos all the way to level 20+ and have a great time, not caring about anything else except buffing before facing the monster in the next room. But I prefer to think that the PCs are moving toward some sort of
endgame that means doing more than killing things and taking their stuff, and
that means engaging with the world
as a world, which means recognizing its conventions as features, not bugs.
Now, I don't totally disagree with you, by all means provide some handwavium! Doskvol simply claims that magic does it, and you can invent stories around growing or stealing food, etc. and that's enough. But don't be fooled, I can go run my BitD game and invent anything regarding food that I care to, nobody can contradict it, and I can 'explain' why the world is how it is, because I can just say "it is so" effectively. Who can contradict me? Consistency in that sense is WAY overrated IMHO.
You need some consistency of physical effect, when you fall you get hurt, that sort of thing. And you need some consistency in terms of the place and role of people in society so that players can reason about fictional position. That's it.
"Need" is a poor term, when discussing recreational entertainment. You don't "need" such entertainment at all, let alone any particular aspect of it. But for me, TTRPGs aren't about what you need, but what you can aspire to, which is an immersive quality that comes from being able to role-play what your character would do in the situations they find themselves in, and having a greater awareness of their world abets that, or at least it always has for me. That requires giving the world a degree of immutability once its conventions are set, and while that immutability is entirely illusory (just like the entire role-playing experience), buying into it is what makes that illusion seem more immersive, akin to turning your cell phone off at the movie theater. The guy who insists on changing the conventions, by contrast, is the guy taking a call three rows over, even though the film is starting.