I don't know what you mean by "meta-explanation".The game world in 4E having a meta explanation doesn’t really work for me. I’ll take BA of 5E to avoid it.
I mean, all RPG gameworlds are authored, and so all have a "meta-explanation" in that sense.
But the reason that Paragon and Epic Tier PCs find the things they're trying to do hard is because they're trying to do hard things - things that 1st level PCs couldn't even attempt (like, eg thrusting their hands into the Dwarven forge to stabilise an artefact that is being reforged; or trying to cow the Djinni in the court of their master Yan-C-Bin).

