That doesn't excuse the lack of world-building though if the goal is an internally consistent world.
A goal of an internally consistent world is a distinct issue. There can be different issues applying to curating a PC list versus a DM monster palette in a consistent world.
I can say I am doing an Alice in wonderland where the PC focus is on Alice types going into Wonderland so while weird PC races are stricken, the first NPC is a white rabbit folk in a Feywild full of disparate fanciful types where that is on theme and appropriate.
There are plenty of valid reasons to have a limited PC range and an open world range.
I ran a gothic horror game and limited PC options to classic D&D races (elves, dwarves, orcs, etc.) and very near human variants (planetouched, shifters, etc.) to provide a theme of a fairly normal base perspective that is not too alien and could do a lot of interactions with society for a gothic horror feel. I did not allow dragonborn or such even though they were in the PH. I did not have harengon bandits but I did have a displacer beast at one point.
I was going for a specific theme and tone for the PC perspective which was very different from say my Wildwood game which had a premise of drawing in people from different worlds and the party ended up with a robot, a tiger folk, a lizardfolk, an elan, a tiefling, and others from multiple different worlds. In the gothic horror game if I am going for a theme of humans turned into monsters as a horror element it has a lot more impact if you are a person thinking about turning into an inhuman monster than if you start from the perspective of an inhuman monster.
A group of PCs encounter a gang of haregon bandits along the road. Ok, why are the bandits haregon? Are they natives of the area? If so, why have the PCs not encountered them before? If they are not natives, why are they here and where did they come from? Are the just refugees from a distant land, exiles from the feywild, or just a couple unlucky sods who stumbled through a portal from Gods-know-where? Why are they hostile? Are they feared, hated, or misunderstood? Could they have gone to the next town and gotten honest work if they wanted, or would they be perpetually shunned to a life of banditry on the outside of town? Are they inherently evil (or have a reputation to be)? What do the PCs know about them: lore, rumors, legends, or are they completely clueless? What happens when the PCs stop and parley with them or capture and interrogate them?
All that stems from one encounter. I guess if they act as one-dimensional HP sacks that fight to the death and exist to be defeated and looted, it doesn't matter. Haregon bandits replace goblins, orcs, elves, or human bandits and it works the same. But if the goal is internal consistency, it SHOULD matter.
Now, I think the same situation could easily apply to any PC as well. If a player came to me and asked "Can I play a haregon" I would have to ask the exact same questions. Are the natives or foreigners? Where do they come from? How do others think and react to them? There is trivial difference except perhaps the PC might need a greater amount of depth. (Or they may not, if the answer is "you fell through a portal" then the answer of where you came from is immaterial. What matters is you're here now.)
Right but the impact is fairly different. One band having come through a portal into Lankhmar and these are the only rabbit folk in the world is interesting for that story point.
A PC being the only rabbit folk in Lankhmar has a completely different story impact as it is how most people will interact with that PC again and again. It can turn it into a Cerebus comic feel instead of a Lankhmar one.
Which leads to a situation where most DMs punt on the question on where the NPC haregon bandits come under the hopes it won't matter, but don't on the PC haregon because it always will matter.
Yeah, they will usually say they are not common or whatever and leave it at that. Or use whatever default description there is from the Harengon entry (which I am not familiar with).
My argument is "if you are curtailing things because they don't fit if your vision for the world, that vision should contain monsters as well."
Sure. If you say no orc PCs because there are no orcs on Krynn then there should not be orcs on Krynn at base absent a planar invasion or such.
That would be different though than saying no PC orcs because I run a good guys game and in this world orcs exist but are inherently evil.
Otherwise, such curation isn't being made for consistency or vision as much as for personal taste masquerading as such.
I am not sure why it would be personal taste masquerading as vision. It could be, but that seems to generalize one option into a generality.
Which is a nice way of saying "if you're going to ban haregon, do it because you hate furries and not because you feel they don't match the tone of Greyhawk".
It is perfectly fine to feel they do not match the tone of Greyhawk. I expect many who say harengon do not match the tone of Greyhawk will not put random rabbit folk bandits in their Greyhawk games as an indigenous population in the Shield Lands. Same thing for dragonborn.
They might save such rabbit folk for a one off NPC encounter in
Dungeonland though.
