Like most religions and other lived traditions, Buddhism has many schools and variants.But I think it is pretty mainstream to uphold the doctrine that an enlightened person dwells in the "four divine abodes": equanimity, compassion, loving kindness and sympathetic joy. That is not a doctrine of mere annihilationism.
This is also brought out in the
Lesser Discourse on the Stems of Anguish. The Jains say to the Buddha, "Friend Gotama, pleasure is not to be gained through pleasure; pleasure is to be gained through pain. For were pleasure to be gained through pleasure, then King Seniya Bimbisāra of Magadha would gain pleasure, since he abides in greater pleasure than the venerable Gotama." The Buddha replies that, unlike the king, he is able to abide, without moving a muscle, for days and nights of meditation, experiencing pleasure - whereas the implication is that the king's pleasure is more fleeting and unstable, depending upon the presence or absence of external, worldly things.
There are interesting discussions to be had - probably not on these boards - about the psychological plausibility of the Buddha's claim about meditation and pleasure. But it seems clear to me that he is insisting that a person who is enlightened (in the Buddhist sense) and therefore steps off the wheel of suffering is not stepping off the wheel into annihilation, but is stepping off the wheel into a state of pleasure. I'm sure there is a reading of this consistent with @
The Shadow's claim that evil (in this case, suffering) is a privation of good (in this case, pleasure) rather than self-subsistent.
That's a fair point and as you say there are different schools of thought in Buddhism: the Mahayana and Theravada conceptions of nirvana are significantly different from one another and some sects, like Pure Land Buddhism, have even more different interpretations. Nonetheless, a key teaching of Buddhism is that life is suffering and that absent enlightenment, it is interminable. What's more, the goal of Buddhism is to disconnect oneself from the temporal world and to end the cycle of rebirth which (again) only results in further suffering (something that only becomes possible upon enlightenment).
Exactly what happens when reincarnation is halted differs from one sect to another, but a fairly wide belief is that the ego ceases to exist, since it is after all, an illusion and there is no such thing as a permanent soul (reincarnation here's a bit more complex of a subject than in Hinduism, where there is a soul). Whether this means unity with a universal consciousness or simple annihilation varies, but in a lot of cases the individual ceases to exist (and this is good, because individuality means suffering).
As you said though, there are limitations to discussing this subject on this forum and I'd say it's not terribly relevant to the concept of the Great Wheel generally. My main point was that the idea of good and evil in "Eastern" religions and philosophies is a very complex one, because there's actually a lot of different perspectives on the subject. Taoism, Buddhism, Hinduism, Shinto, and Confucianism all have pretty different views on the cosmological order and what good and evil entail.
There are limitations on this board, and this thread, as a forum for discussing the metaphysics of morals. But at the risk of being simplistic, neither of these claims is easily defended.
I think the point being made was that while absolute standards of good and evil may or may not exist in the real world, they definitely exist in D&D. Celestials are made of supernatural (and absolute) good. Fiends are made of supernatural (and absolute) evil. Which means there's certain limitations in talking about moral relativism in D&D (although it's a discussion I welcome all the same, being somewhere between absolutism and relativism myself).
Many people who play D&D don't regard it primarily as a story - a collection of canonical background events, history, etc. They regard it as a (loose) collection of tropes whose expression occurs via a mixture of flavour text and game mechanics.
And that is something worth remembering, though as always, even the core rules infer a fair amount of fluff. How much fluff they should infer and how much they should leave vague is a ground for debate though.
When it comes to cosmology, the Great Wheel has a strong argument for precedent - it was included in 1st edition, 2nd edition, and 3rd edition, and even had a very limited form of support during 4th edition. As far as any "core" cosmology goes, the Great Wheel has a better argument than anything else. That being said, I can see a strong argument being made for the core rulebooks supporting a number of alternate cosmologies as well: mentioning the World Axis from 4e, the cosmological order of Eberron, etc. as valid alternatives. That's not what the designers chose to do, but I can see why some people might prefer that.
It's far more than a favored concept. Let me try to put this another way.
Perhaps what Planescape /should/ have done is published an adventure that is hubbed in a different "center of the multiverse." A city similar to Sigil but that conceives of the outer planes as... plateaus and valleys on a great mountain, to choose one of your examples. Is that city a floating ring? Not likely. It might be at the summit of the mountain, but it won't be speared by it like a wheel on an axle. The city is going to share aspects of its conception of the planes. It's going to have its own truisms and philosophies that reflect that conception. It's probably going to have its own factions, governed by an entirely unfamiliar alignment system. And on top of everything else, it's probably going to have a completely new set of prime material worlds, all of whom conceive of the planes like plateaus and valleys on a great mountain.
But Planescape didn't do that. Planescape wove the Unity of Rings and the Great Wheel into every fiber of its being. Saying that the Great Wheel is only one way of looking at Planescape is like saying the map of Toril is only one way of looking at the Forgotten Realms. Technically true. Practically false.
I think that's a fair point. For the most part, Planescape itself doesn't really challenge the Great Wheel in any significant way, at least not outside of the other "roads" between the planes mentioned briefly in the original release (Olympus, Styx, etc.). For the most part, the Great Wheel is an assumption held by Planescape, rather than just a favored concept.
That being said, Planescape does open itself up to other interpretations (even if it doesn't really embrace them) and the bias shown toward the Great Wheel may simply be a result of the fact that Sigil is the setting's core location (the equivalent of Waterdeep in the Forgotten Realms or the Free City in Greyhawk). Most of the material for Planescape is written around the assumption that the PCs are based out of Sigil itself, rather than various Primes or the Outer Planes (or Inner Planes), so the attitudes and conceptions of Sigil are those of Planescape by default. Likewise, in the Forgotten Realms, there's a clear bias in a lot of the sourcebooks towards the values of West Faerun, which often puts other parts of the continent (not to mention Zakhara, Maztica, and Kara-Tur) at a disadvantage. The Celestial Bureaucracy don't really mesh very well with the Faerunian pantheon and their various escapades, but both are canonical versions of gods on Toril; it's just that the Faerunian pantheon gets a lot more attention from both fans and designers.
So while you're right that Planescape doesn't do a very good job of supporting other cosmologies outside of the Great Wheel, I think it's fair to say it does't preclude them by any means.
