Chaosmancer
Legend
To teach DMs how to play they game.
You seem to be confused. The chapter in the DMG is about teaching DMs how to build a world. The Player's Handbook will cover most of how to play the game, and the Encounter Building and Adventure building chapters will cover the rest.
Yeah. At High Level.
5e and the 2024 version will have players as big mall of world changing power and coursing with magic at level one.
Many races get spells.
Magic is a feat away
Most of the subclasses of no casters give magic or warp reality by level THREE.
PCs can slaughter evil humaniod scout parties without a sweat.
This warped the sensibilities and themes of zeroes becoming major forces later that most old setting ran on because they were built on 1e or 2e.
I'm sorry, maybe I'm confused. Wasn't Greyhawk the official setting for 3.X? The edition of the game with CoDzilla? The edition of the game where the scaling was so insane a DC 60 check to run on clouds was viable, and people made characters of tremendously monstrous power?
PCs slaughtering evil humanoids is a given at most levels, and the rest of this seems to be focused on this idea that country-rulers can't compete. When I'm pretty sure the former mayor of the Free City of Greyhawk ascended ot become a God, the ruler of the evil country is a Demi-God who fought Vecna, Vecna CAME from Greyhawk.... I don't think the setting is going to shatter like a glass plate at the power of a 3rd level 5e character any more than any other setting has.
Limiting info load on new players.
Sure, they could do that... or they could take those elements as the things that make the setting different and emphasize them. Prevent that whole Catch-22 you were talking about where any setting must become the Forgotten Realms.
BBEGs meant to be defeated, NPC relationships, weaving personal side quests into the main plot.
The Archmages, liches, warrior kings, and wandering NPC parties.
Nothing in Greyhawk prevents any of this? Half the BBEGs in the various books STARTED in Greyhawk.