Honestly, give how barebones the 1E depiction is, even the box set, and that it is written by an obviously biased unreliable narrator as a tool to let DMs customize...I never saw any conflict between rimming the OG Greyhawk with stuff like Goliath and Dragon on, etc.
So, the word that was used several times was "consultant"...with Widlemoint, Mercer and Co did a lot of work, with supervision and close help from the core D&D team whipping it into shape. The panel going on at GaryCon right now has Justice Arman with Luke Gygax, so they may go into more detail...
Yup, Daggerheart is a pretty creative 2d12 resolution system.
Cosmere uses a roll over d20 resolution system, so the math in the core mechanic is not un-D&D-ish, but other than a surface level of the GM asking a player to roll a d20 for action resolution it is not a 3E/5E derived system overall.
Right, but the fallout when a lot of those sorts of things started getting revealed is when WotC distanced themselves from most of the celebrity D&D scene.
We have had Widlemoint, we have had Witch light, we have had the many Settings of the Radiant Citadel.
Mostly, third parties have absolutely exploded with Settings in the past decade, and at this point WotC is putting those up on Beyond.
Just clarifying the timeline, I honestly don't know what it means: but the most explicit Dark Sun test came well after the shakeup Ayoub was describing.