Urriak Uruk
Gaming is fun, and fun is for everyone
Like I said before, considering that Greyhawk is such a tiny slice of Oerth, the notion that a given race can't exist in the setting because of "canon" seems just flat out bizarre to me.
It would be like looking at only one continent in the real world and then deciding that Kangaroos can't exist. Or Gorillas.It's a big, big world out there. We've already got Yuan-ti and other scaley stuff in Greyhawk. Never minding the really weird stuff like Yak Folk. Seems that adding in Dragonborn or virtually any other core race isn't really much of a stretch.
I guess, if we're going to go with the "canon" appeal of Greyhawk, then sorcerers, and warlocks should be off the table too. After all, they're later additions. If we're sticking to the original boxed set, then barbarian is off the table too. They weren't in Greyhawk as a class.
There's an awful lot of D&D stuff out there that gets stripped out of the setting if we're going to go down this route. You like Aboleth? Too bad, that's from the Monster Manual II. That's not canon. Animal Lords? Sorry, can't have them. Tasloi? Nope.
On and on. There's a host of stuff that gets left on the table if we really want to go down this route.
I don't think anyone is saying that Dragonborn can't be in Oerth; they obviously can, especially for someone's home-game. I think what some people (at least, I am) are arguing is that Dragonborn shouldn't be shoved into Oerth as a core race with a flimsy explanation.
For example, Dragonborn were added into Forgotten Realms with this big Spellplague event that shoved two world Abeir and Toril together, where they flipped some continents, but then they flipped back but some Dragonborn stayed... I honestly can't explain it very well because it doesn't make much sense.
What I'm trying to say is adding Dragonborn into Oerth can be done, but it should be done in a hand-wavey kind of way, like "Dragonborn were always here in this kingdom in the middle of the forest that we never mentioned before now."
I think the way tieflings were added in GoS is a pretty good metric for how Dragonborn could be done. There's only one tiefling, she's named to be from an area of the world famous for being run by a cambion, and it's pointed out how the locals find tieflings completely foreign and terrifying (compared to humans/elves/dwarves that people are used to).
If an official D&D product threw in a Dragonborn NPC and said he was a traveler from the Draconic Imperium of Lynn, this would feel like a natural expansion of the lore of Greyhawk that even complements the material already published. Nothing already published is contradicted, and the overall setting is made richer for it.
If you're curious, the Draconic Imperium was mentioned in "Dragon Annual 1" (I don't have a copy but I can squint at the words in this link on page 72: Dragon Magazine Annual #1 - 1996.pdf). I believe that area of the world may also be the setting for the French graphic novels "Black Moon Chronicles," but don't quote me on that.