It's the positives and negatives of "leveling" as a character advancement. In order to make leveling seem worthwhile you have to make noticeable jumps in power with each level, but doing that widens the gap between either end of the leveling system that it turns the narrative of these character into something goofy and you can't create anything remotely realistic.
Look no further than World of Warcraft where you have bears your PC can fight that are 3rd level in starting zones, as well as bears that are 60th level in the latest expansion. Those levels mean absolutely nothing related to story-- bears are bears and there's absolutely no reason why one bear can be killed when you first start out as a PC, but another bear would decimate you with a single swipe. It makes no narrative sense, it's only there for game purposes.
And this is true across the board. There's no way there can be any universal system in D&D that aligns levels and leveling to the in-world story of the characters. There's just too many places where one gets forsaken to the other.