I think that's the difference between fantasy fiction, where the author isn't constrained by balance issues, and an RPG.
Look at Wheel of Time. Rand 'al Thor is a....what, 20 year old kid, who is a better fighter than all the fighters in the land, and a better channeler than the rest as well.
Particularly in your 4-man party of D&D adventurers, you can't simulate that very well, because that would mean either one character is way more powerful than the other PCs, or he's not as powerful as he's supposed to be according to the fiction.