Parmandur
Book-Friend, he/him
Well when you put a superman in the game it behoves you to put Kryptonite in the story it when it takes extreme/weird measures like inducing a oath bound hero like Cu Chulainn to eat dog to defeat him that is evidence of power and how normal circumstances really arent a threat....
It is by no means evidence they are somehow within reach of low level threats.
Not so much within reach, as in the same world. As the DMG outlines, it's pretty easy to take the bounded numbers, but play it Wuxia, or Celtic myth. No need for the numbers to change, if you change the narrative representation.
Still, a Level 20 PC isn't likely to be killed by a legion of Goblins, but putting defeat utterly out if reach isn't the style the game went for. That sort of "outleveling" of threats is...eh.