If your point is that if you want to give them a dwarven trait in the PHB you have to use the PHB... well, duh. That is blatantly obvious and also beside the point.
But also, man some of those traits are legitimately pointless for an NPC. For Example, Stonecunning. You are considered to have expertise in history when it regards stonework, but in reality, since NPCs will likely never roll for history, especially a dwarf for stonework history, it isn't worth giving to a dwarven character. Just like I don't bother taking a commoner and giving them Sleight of Hand to represent a street urchin picking pockets.
But, sure, I will admit that if I want an NPC to have a PHB racial trait, I need to refer to the PHB Racials Traits. And if I want them to have a magical item from the DMG I refer to magical items from the DMG.
The real point is though, that I am not required to use those, if I don't want to.
Right, you don't have to do anything. But Wizards only provided guidelines for one approach at the beginning of 5E, which indicates their original assumption that for PHB races, PCs and NPCs had the same traits.
So, we are now at the point where those Racial ASIs are not relevant to NPC statblocks because they can have any numbers, and likely will just have the stats they need for both flavor and having the right attacks and DCs.
No, we are at the point where ASIs could have been applied to their scores, and simply not noticeable in a statblock that doesn't conveniently have all 10s.
And then you want to say that I can't use exceptions to prove rules, but what I am doing is showing that exceptions exist. By the way, look at the Hobgoblin and Hobgoblin Commander in the MM, also no Save Face Trait and "hobgoblin" is about as generic as we can get, since we don't have stats for "generic hobgoblin". Now, that was because Volos came out later, but again, if they didn't feel the need to update the Statblock, then are we really supposed to add these traits to generic hobgoblins? Or were they telling us that PCs and NPCs are different, by treating NPCs and PCs differently?
There is not a single Hobgoblin Statblock officially released that uses Save Face. Know what they do have almost exclusively? Martial Advantage. A trait that no PC Hobgoblin can access. Did you know that no NPC Bugbear statblock has a reach like a PC does? Did you know that they all have the Trait Brute, which a PC cannot access?
Or, when they examined these monsters for use as PC races, they re-evaluated what their traits should be, to balance them with the other PC races. It doesn't mean that they had suddenly decided PCs and NPCs were fundamentally different, only that they updated their idea of what the races were like at the baseline.
So even in 2e NPCs and PCs were not meant to be identical?
Wait, we're talking about 2E now? That's a whole different ballgame. For starters, monsters didn't even have a full set of ability scores...
It seems like a stretch to try and claim a subrace when no subrace is labeled. Especially since, per the lore, Dragonborn don't have their abilities because of a "true breeding" of their bloodlines. It is all muddled up to the point where two black scaled dragonborn who breath ice could give birth to a red scaled dragonborn who breathes lightning (and actually they are majority brown scaled I've heard).
It seems to me that you are only trying to claim such, so you can say that "not all subraces give different ASIs, so you can't use subraces like you were trying to use them," when this would be the only example, and it is relabeling something that has not previously been labeled as such.
You're extrapolating way more from what I said than what was intended. All I pointed out is that you could see dragonborn of different colors as subraces, if you wanted to, and then you tried to use that to somehow prove that was an argument in favor of "subraces exist" justifying a floating ASI for the entire species, to which I said it really didn't.
I enjoy how you dismiss one of the strongest pieces of evidence I have as not supporting either side. The Lizardfolk Commoner is A) A commoner, letting them be a "generic member of the race", B) Officially printed and statted in an Official Product C) released after volo's and any changes to the Lizardfolk design that was entailed by Volo's and D) Completely unlike the PC version in Volo's. It does not have their iconic Hungry Jaws and it has a massively inflated strength score, despite Lizardfolk not giving a bonus to Strength. It meets all the criterion you have placed for what we should be looking for, and supports my postion that NPCs are not treated like PCs.
Actually, I went back and looked at the lizardfolk commoner. You're right, it doesn't reflect Volo's. But it is broadly consistent with the DMG NPC Features. Its highest stat is Strength, its lowest stat is Int, plus Hold Breath, +3 AC, swim 30 ft, and Draconic language. It could mean that they'd decided on PCs and NPCs as being different... in 2019. Or it could mean they just ignored Volo's for this book.
(Also, realistically, it's probably just designed to be a weaker version of the MM lizardfolk statblock, and it's not actually a commoner at all.)
It seems like all you are trying to do is prove that in 2014 they wanted all NPCs of a race to use PC abilities, based on the fact that they said if you want to use PC abilities for them you should use the PHB. Then acknowledge that in 2017 they had changed their mind on that, so that you can be upset in 2021 for them changing their mind YEARS ago.
I mean, I can concede that wizards intended in the beginning of the game that if you wanted to give a character hill dwarf traits that they wanted you to read the section on hill dwarf traits. That is the same as conceding that if you wanted to give them sneak attack they wanted you to read the section on sneak attack.
But, taking it that step further, and saying that if I wanted to have a dwarf NPC I was required to give them the PHB stats, ASIs and abilities and all? While at the same time acknowledging that the NPC monster blocks in the front of the book are specialized with their ASIs and may not reflect the generic member of that race? That is not only a bridge too far, but one that is unsupported since you immediately undermine it with exactly the point I keep making.
NPCs are not treated like PCs.
You weren't required to do anything for NPC design. But Wizards had a certain expectation at the beginning of 5E, that PCs and NPCs for PHB races were treated the same. Maybe that changed in 2016. Or 2018. Or 2019. But they never made any statement on the matter until 2020, in the leadup to Tasha's.
That means we have to go with the evidence of the books. In 2014, they very clearly weren't meant to be different, or at least not significantly different. From 2015-2019, the evidence is ambiguous and uneven at best, and could reflect changes in baseline expectations for the race, or adjustments made purely for player balance rather than a philosophical shift. Then in 2020, they finally made an official assertion that PCs are archetypes that don't reflect NPC members of the race.
Also, I'm not especially upset with them. I just think they're implying this was the idea all along, and quite simply, I don't think it was.