Dwarves aren't cool anymore

[Psyren]

Third party, but included on the officially branded and hosted resource seems like it should count.

No - the whole argument that started the counting tangent was whether WotC is printing too much or too little race stuff. Third parties are not WotC.

On potency of racial traits:

Why do the traits need to be at or below "first level" of power?

Because those traits will be available to first-level characters.

I'm not saying they can't spike above, say, a 1st-level spell, nor that they can't ever scale as OldTrees1 correctly stated, but the nature of the ability needs to be taken into account at that point too. A 2nd-level spell like Misty Step or Spider Climb is an okay ability for a first-level character, while one like Scorching Ray or Moonbeam would not be. Invisibility would be fine if it doesn't last for an hour like the spell does. That kind of game designer judgment of the ability is what is needed.

I can understand not wanting to eclipse an entire class, or give something that allows, say, spamming a 3rd level spell as a racial trait. Mechanically, though, I don't understand why it isn't appropriate to have traits that can be impactful through the spectrum of class levels and not trivialized once you hit 3rd/5th/whatever level.

As mentioned, I'm fine with racials that are useful at higher levels, whether due to being things that are always useful (like bonus action teleportation) or that scale with level (like a pool of healing dice.) I think most modern racials fall into one of these categories in fact; I can't think of any off the top of my head that become "trivialized once you hit 3rd/5th level" as you claim, though there's certainly a shift where the degree of power coming from your class and feats eclipses what comes from your race more and more, but that's to be expected. The bulk of your power should come from your build choices throughout your career, not a single choice you made at the start of the campaign.