You can disagree all you like, it doesn't make it not true.
Okay. Your insistence that it is true does not make it true either.
Beliefs are not real? That's a fairly controversial theological position.
That isn't what was said. What was said is that it
literally does not have a truth value, but rather that each individual's perception is true
for them and no one else.
Beliefs are what they are. But when
anyone's perception is allegedly equally valid no matter how that perception differs, we live in a world without facts. That's not an acceptable world building principle in my book.
Particularly when, as noted, you can just use divination magic to directly view these places while not being located inside them.
I'm not sure what you're talking about here. The Great Wheel and the World Axis are simply diagrams, a map of extradimensional concepts and their connections to each other. What claims are they making?
GW: Sapient souls automatically, always, and inherently go to one specific portion of reality upon the death of the body that that soul belonged to. This is simply a fact of reality that can neither be changed nor rejected, only delayed or forestalled by trapping a soul so it cannot go to the portion of reality that reality itself assigned to it.
WA:
Some Sapient souls go, as designed by the beings who desired this effect to occur (the gods), to the realm of the god they worshiped or who was most similar to that person's behavior in life. Other souls simply go to the general afterlife place and have no home nor safe haven, and if they
tried to go to their preferred deity's domain, that domain would slowly
destroy them simply for trying to exist there for too long, which is
not what the gods designed the afterlife to work like.
These are clear, specific, testable, empirically-verifiable claims about how existence works. They are also contradictory. I could come up with more, of course, but that is the most overt and obvious difference between them. Likewise, one of the most overt and obvious differences between the "World Tree cosmology" (not to be confused with the
actual tree called the World Tree, which is a component of the 5e version of the Great Wheel and not a cosmological framework) is that several planes in the Great Wheel
explicitly do not exist in the World Tree cosmology, and several planes in the World Tree cosmology
explicitly do not exist in the Great Wheel.
Like, let's say you're using the Great Wheel for your setting. You can also decide in your setting that instead of going to the planes when they die, all souls go to Hades/Grey Waste (identically to Eberron's Dolurrh) to be cosmically recycled (or whatever else happens when souls disappear). Removing petitioners and changing the cycle of souls doesn't mean you aren't using the Great Wheel still.
You have just changed the Great Wheel almost irrevocably, just with that one singular alteration. The whole absolute alignment enforcement thing is, very specifically, one of the greatest (and IMO worst) calling cards of the Great Wheel.
What I love about 4e lore and the World Axis is so tight and works together like real world mythology. That drew me into the PoL setting more than any previous setting. It is great from that aspect.
I flatly disagree that it is "so tight" because that's precisely what it aimed
not to be. It aimed to be
open, as every real world mythology has been open. It's almost entirely built out of
stories about things and (godly-level) people, and it has several components where the true answer to a question has been explicitly lost or hidden and only messy, unverifiable tales remain. The origin of dragonborn, for example. Everyone knows that Io is the progenitor of dragons. Nobody
actually knows who created dragonborn anymore, and none of the proposed theories is free of obvious self-serving bias for one group or another.
However, I spend an inordinate amount of time working on deities and similar exalted beings (love me some primordials). At some point I realized the tight PoL setting didn't make sense for my understanding of the divine (and similiar entities). My default assumption when it comes to deities, and by proxy the cosmos, is that mortals do not, and possibly cannot, understand them. Therefore, and myth, tale, or cosmology mortals develops is invariable wrong to some degree or another. So a tidy cosmology / lore didn't make sense to me from that perspective.
How does this comport, then, with the explicit claims, not about "the divine" etc., but about whether certain planes
even exist or not? About whether souls literally do instantly zorp to the plane assigned to them by the reality-enforced alignment chart or not? About whether parts of planes cleave off one and glue onto another? Etc., etc. These have nothing to do with the divine and are consistently verifiable for anyone who has access to the tools to do so. Just because it's expensive or difficult to do doesn't mean it's not empirically verifiable.
So, back when I played 4e, I started thinking of ways to modify the default 4e setting to make it less comprehensible. First and foremost was that any idea of the cosmology would be incorrect. Any description of the cosmos is limited by our ability to observe, describe, and understand its true nature. That was freeing. Now, it so happens the easy, and nostalgic, thing to do to add some crazy was to mash it with the great wheel, so I started working on that. What I came up with ended up being very similar to what became the 5e cosmos (mine had some differences), so I was surprised to see my work in the 2014 DMG!
I just don't understand how you get
less comprehensibility by adding the Great Wheel, which is literally all about confining things as much as possible to their narrow, predefined, enforced niches and
literally rearranging reality to ensure that they can never truly leave those niches. Any other cosmology, even the World Tree cosmology, would be better than this.
Well that is an extreme take, but again that seems to be the way you go. I don't know how I can discuss this with you if you always go to extremes. Saying we don't know is not a rejection of truth. That is the ultimate truth IME.
You did not say you don't know. You said that perception
defines reality. That means if I perceive blue and you perceive red,
we are somehow both right. Doing that deletes the very possibility of truth in the first place. Reality becomes "well, how do you
feel about the metaphysical concept here?" It isn't that each of us has an incomplete, tiny sliver of truth that we struggle to communicate to anyone else. It's that there
never was a truth for our feelings and sensations to correspond to, because every feeling and sensation, no matter how divergent, is somehow equally true.
Regarding RPG products. Some like everything spelled out, some like it vague. That is OK and neither is a rejection of truth.
Certainly. I never said otherwise. I said that if perception IS reality (which you and others have said), and different perceptions are equally true despite being explicitly contradictory (which is the position you have specifically advanced), then "truth" no longer has any meaning and there are no such things as facts at all. (Specifically, the logical reason here is that even one contradiction permits you to "prove" any statement you like no matter what that statement is, via the principle of explosion. Most people have a rough and unrigorous, but still loosely correct, sense of why a proven contradiction would be bad news bears.)
That is your take on what it says, but that is not fundamentally what it says. We are both colored by our viewpoints. I am aware of that, I am not sure you are.
How else am I supposed to interpret statements like, and I quote, "For your campaign, you can use a different model of the planes."?
That is quite explicitly saying that YOU can decide YOUR campaign works "different"ly. In other words, it is telling you want is in fact objectively true, including a number of things that can be empirically verified, but you can decide to do something else if you really feel like it. It then spends literally only a few sentences talking about these things...and at least 100x as much space going into lavish detail about the Great Wheel and all its specific (and empirically verifiable!) characteristics. One cosmology is clearly the favorite here. Nothing, not one thing, is presented as making the Great Wheel an awkward fit, a failure to account for something that really does exist (unless you yourself fiat declare so) or that asserts the existence of something that in fact does not exist (unless you yourself fiat declare so). This is nothing like real world competing theories nor stories. It is—to use your own terms—
far to tight and consistent. It is far too thematically closed, far too (as the 4e devs rightly put it)
needlessly symmetric, not because that symmetry was useful for world building but because it was necessary in order to enforce straightjacket alignment onto
all of reality.