To be honest, this would make sense if they updated the world, but not if they didn’t.
We very rarely get updates in old world content, and when we do it usually makes no sense. Like having Cata Garrosh in MoP, when he canonically doesn’t have Gorehowl, even though he’s now randomly carrying it there even though he shouldn’t be.
What sense would it make for Allerian Stronghold or Quel’danil to be populated by Void Elves when they’re old, un-updated content besides that?
Unless you just mean stuff from SW/BfA onwards, in which case I don’t really have an issue with that.
I never understood why the Shield Mages/Yvera Dawnwing weren’t Void Elves.