I don't know, why would it?
You seemed to think it should with your comment on it being interesting they didn't have the rules in a third core book.
I don't have a D&D Beyond subscription, but I am capable of searching the monster list. The only official, non-homebrew commoners I can find are the generic commoner, the lizardfolk commoner (which has issues, as both
@Faolyn and I noted), and two others: a goblin commoner and a kobold commoner, both from Tales from the Yawning Portal. Since I have no subscription, I can't determine whether they conform to the DMG guidelines, or Volo's guidelines, or if they're just using the default commoner stat block.
That said, if they do use the generic commoner stat block, that simply means racial traits weren't applied. Also, D&D Beyond isn't infallible, either (though I would agree it's more reliable than 5etools) and has had unofficial stuff under its aegis (such as that racial feat supplement they released on DMs Guild years ago).
I posted the stats a while ago, the Kobolds are full generic commoner. The Goblins have 8 str and are commoners.
And, I think that this is strong evidence of my point. An official product of the official company decided that applying the racial traits was not necessary even as it made Kobold Commoners better in 5/6 stats than their "warrior" counterparts in the MM.
You can say that it is a mistake, but it is literally direct evidence that you can just use the block without the Racial traits as the official default, since the only time they used an official NPC statblock with a race, they didn't use the Racial Traits.
And as I pointed out, that may indeed suggest that "PCs are special" had begun to emerge as an idea sooner than 2020. Or it may just indicate that they had a rethink on their baseline ASIs. Either way, it doesn't have any bearing on how they treated ASIs in the core rules - as a trait that was part of the race's makeup.
So... now the DMG isn't part of the core rules, when it was before?
Or are you saying that since Volo's isn't Core, it gets overwritten despite being the official version of these races, for an optional rule on a table that isn't supported by their digital tool set?
Then I reiterate the question I asked
@Faolyn - if you assume that a generic commoner is meant to represent a member of a nonhuman race as is, does that mean elf NPCs don't have darkvision? That dragonborn NPCs don't have breath weapons?
The only interpretation that makes sense here is that you can use the NPC statblocks as is if you don't want racial traits factored in, or you can reflect their race by applying the racial traits from the PHB or DMG.
That is actually not even the first question that needs to be asked. The first question is "does it matter".
Does it matter if the Elf NPC has darkvision when he is the court mage for the King and isn't in darkness? If he is never in a situation that utilizes Dark Vision, then it doesn't matter if I give him darkvision or not.
But then we get to the gotcha part of this question. If it does matter, and I agree that the elf gets darkvision, does that mean I have to give him longsword proficiency and +2 dex as well?
I mean, I definitely think it would be cool to see a Dragonborn forging a sword by using his breath weapon... which is supposed to be 1/ short rest and would be impossible to do following the rules. Or maybe a bartender using his ice breath to cool drinks... but again, 1/short rest, so by the rules, that would be a complete impossibility. But, what if I do it anyways? Am I then honorbound to give them other traits?
I don't think so. Just like I can give a character a wizard's spellbook and a cantrip, but I don't have to give them any actual spells. That doesn't fit the rules, no character can get a wizard's spellbook and be learning arcane magic enough to cast a cantrip, but not any spells.
Maybe Dragonbreath is hard to master, maybe it is actually a rare trait, maybe any number of things. I as the DM have full authority to decide if my dragonborn can use it and how often, so I don't see the point except to try and point out that it is a trait they are famous for, that by following the rules the commoners wouldn't get, then back-end that to force me to accept giving them all the same ASIs as well.
First of all, when did I say floating ASIs were "bad"? I already said I don't really have a position on fixed vs. floating. I just want continued support for fixed ASIs as well, so folks who liked having defaults for character races can still get them.
Second, humans don't count for this discussion, because only the variant human has floating ASI in the core rules. The default human gets +1 to all six stats. If you pick variant human, you're already not a casual player, you're looking to customize.
Third, it is true that two existing races have partial floating ASI - the changeling and the half-elf. However, those both still provide some partial guidance for folks who want it, which is better than zero guidance. (Also, now I wonder how popular the changeling and half-elf are with casual players.)
Fourth, sure, Wizards is perfectly capable of establishing a character race so adaptable and formless that it wouldn't have any typical ASIs. But so what? You're still making things more complicated for folks who liked having suggestions. (In fact, similar to changelings and half-elves, I wonder how popular such a character race would have been with casual players.) I don't see the harm in throwing some recommendations in with them.
Four existing races. Changeling, Half-Elf, Warforged and Simic.
As for how popular, looking around on the internet I found the chart people have been posting. Simic doesn't break top 20. Changeling is 0.54% Warforged is 0.66% and Half-elf is 3rd place overall with 9.53% (only beaten by Elf and Human. Human by the way gets 21.17% though it isn't possible to tell how much of that is floating. Elf is 13.66% )
Now, where this data is interesting is that the Half-Elf is the only one of these races in the PHB. The others are Eberron or Ravnica specific. And the gap is fairly significant.
4th place Tiefling -> 7%
5th place Dwarf -> 6.22%
6th Place Dragonborn -> 6.03%
I also enjoy how Variant Human, a core rule race option and the most popular human option as far as we're able to tell, doesn't count. But the DMG optional chart buried in the book that no one really looks out except for dungeon masters customizing monsters does count.
And look, it would be nice if players who want static default ASIs got tossed a bone. But I'm just saying that they already have races that don't do that for them. There are no recommendations for Humans, Changelings, Warforged or Simics, why should we now start demanding recommendations for every race no matter its default? It was okay not to have them before.