Sword of Spirit
Legend
I'm going to refer to the Great Wheel/Planescape cosmology as the D&D Multiverse, because that's what 5e calls it and I don't want to have to clarify what I'm talking about all the time. Alright, so here's how it went:
1e Manual of the Planes:
-The D&D Multiverse was fleshed out from earlier seeds to cover most of the basic ground it does today. There are a lot of differences, but it's essentially the same thing, as opposed to any of the other cosmologies that have been used in D&D settings.
-At this time the main D&D settings were Greyhawk, the Forgotten Realms, and Dragonlance, and (with the possible exception of Dragonlance) they all used the D&D Multiverse.
2e Cosmology:
-The D&D Multiverse got substantially expanded through Planescape (and Spelljammer)
-All worlds existed within the same D&D Multiverse. You could travel between them, and that's something that happened in official sources.
-A few worlds didn't interact terribly well in some of their fiction, but there was often an official explanation (ie, Dark Sun existed in a "closed" crystal sphere, so you couldn't spelljam in or out).
3e Cosmology:
-The only setting that still used the slightly changed D&D Multiverse was Greyhawk.
-Every other setting either didn't get addressed officially in 3e, or got it's own unique cosmology. It was assumed that each setting existed in its own reality, and you could not hop through portals or spelljam from one to another.
-Forgotten Realms got it's own unique cosmology.
-Eberron was created, so it naturally got its own unique cosmology.
4e didn't use the D&D Multiverse, so it isn't comparable.
5e Cosmology:
-As of the original publication of the core books, the D&D Multiverse now officially encompasses all worlds again, like in 2e.
-Eberron retain it's unique cosmology as a mini-cosmology within the D&D Multiverse. Basically, the same treatment that Dark Sun got in 2e.
-I do not have any of the Magic: the Gathering setting books, and without them it is unclear how or if this applies to them. They might very well exist within their own cosmologies.
So basically, originally (or as near as you can get to it) most settings existed within the D&D Multiverse. 3e decided to buck the trend, and 5e went back to it.
I can understand how someone might see the D&D Multiverse as applying particularly to Forgotten Realms if looking at it compared to M:tG settings, but that misconception causes confusion regarding a lot of things. For instance, the racial pantheons (elves, dwarves, gnomes, drow, etc) are D&D Multiverse, not Forgotten Realms things. You'll find the same pantheons in Greyhawk, Planescape, and Spelljammer, and they are generally offered as recommended options for home-brew settings (along with the fantasy-historical pantheons). In fact, the Elven, Dwarven, Greek, Norse, and Celtic pantheons are considered to be the top five powerhouse pantheons in Planescape (at least as far as the Sigil people know).
There are so many things that people mistakenly equate as Forgotten Realms specifics or add-ons that are in fact D&D Multiverse things--many of which predated the Forgotten Realms and first appeared in Greyhawk and other places!
It feels to me kind of like if the D&D Multiverse is Basketball and the Forgotten Realms is Michael Jordan, but people believe he invented the game and owns the NBA or something.
"That's not how that works! That's not how any of this works!"
1e Manual of the Planes:
-The D&D Multiverse was fleshed out from earlier seeds to cover most of the basic ground it does today. There are a lot of differences, but it's essentially the same thing, as opposed to any of the other cosmologies that have been used in D&D settings.
-At this time the main D&D settings were Greyhawk, the Forgotten Realms, and Dragonlance, and (with the possible exception of Dragonlance) they all used the D&D Multiverse.
2e Cosmology:
-The D&D Multiverse got substantially expanded through Planescape (and Spelljammer)
-All worlds existed within the same D&D Multiverse. You could travel between them, and that's something that happened in official sources.
-A few worlds didn't interact terribly well in some of their fiction, but there was often an official explanation (ie, Dark Sun existed in a "closed" crystal sphere, so you couldn't spelljam in or out).
3e Cosmology:
-The only setting that still used the slightly changed D&D Multiverse was Greyhawk.
-Every other setting either didn't get addressed officially in 3e, or got it's own unique cosmology. It was assumed that each setting existed in its own reality, and you could not hop through portals or spelljam from one to another.
-Forgotten Realms got it's own unique cosmology.
-Eberron was created, so it naturally got its own unique cosmology.
4e didn't use the D&D Multiverse, so it isn't comparable.
5e Cosmology:
-As of the original publication of the core books, the D&D Multiverse now officially encompasses all worlds again, like in 2e.
-Eberron retain it's unique cosmology as a mini-cosmology within the D&D Multiverse. Basically, the same treatment that Dark Sun got in 2e.
-I do not have any of the Magic: the Gathering setting books, and without them it is unclear how or if this applies to them. They might very well exist within their own cosmologies.
So basically, originally (or as near as you can get to it) most settings existed within the D&D Multiverse. 3e decided to buck the trend, and 5e went back to it.
I can understand how someone might see the D&D Multiverse as applying particularly to Forgotten Realms if looking at it compared to M:tG settings, but that misconception causes confusion regarding a lot of things. For instance, the racial pantheons (elves, dwarves, gnomes, drow, etc) are D&D Multiverse, not Forgotten Realms things. You'll find the same pantheons in Greyhawk, Planescape, and Spelljammer, and they are generally offered as recommended options for home-brew settings (along with the fantasy-historical pantheons). In fact, the Elven, Dwarven, Greek, Norse, and Celtic pantheons are considered to be the top five powerhouse pantheons in Planescape (at least as far as the Sigil people know).
There are so many things that people mistakenly equate as Forgotten Realms specifics or add-ons that are in fact D&D Multiverse things--many of which predated the Forgotten Realms and first appeared in Greyhawk and other places!
It feels to me kind of like if the D&D Multiverse is Basketball and the Forgotten Realms is Michael Jordan, but people believe he invented the game and owns the NBA or something.
"That's not how that works! That's not how any of this works!"