The issue here, if you want to call it such, is that this doesn't actually "solve" anything. If we're just talking about different ways to distribute mechanics in a game absent any further context, then it works fine, but so does attaching the same mechanics to race/species/ancestry/etc. At most, it increases design space for customization, which can be seen as a positive or negative depending on how complex you want character creation to be. But as a measure to resolve perceived negative correlations to real life issues (e.g. racism), it's just passing the buck. Stereotyping ethnicities and stereotyping cultures are both problems in the real world, so trading one for the other doesn't seem like an improvement, really.
Frankly, I think the biggest flaw in the racial mechanic setup (in modern editions) is that D&D was designed as a game about archetypes. It wasn't problematic to have all elf or dwarf characters in Basic D&D essentially be the same mechanically because PCs weren't supposed to be reflections of the greater populace around them. They were exceptional. It wasn't until WotC got their hands on the game that suddenly PCs and NPCs played by the same rules, so now if the PHB race write-up says that PC elves are all trained in longsword and longbows, it meant all NPC elves were assumed to be as well. And as the class/race structure became less about archetypes and more about toolkits used to build the character you want a la carte, the assumptions of training and other learned abilities made less sense to be attached to the race chassis. But that same reasoning applies to culture outside of minor things like language. Background makes the most sense for learned mechanical features.
Honestly, I think that the biggest way to resolve any of this is just to assume mechanical uniqueness for PCs. As long as their character creation isn't assumed to be reflected by the NPCs around them, then how you divide up the mechanics is just a question of desired granularity.