It is not acceptable because it is utterly meaningless. There's no way that a scale can represent something that is intrinsically subjective.

on my resume I list specific skills (i.e. AWS, Node.js) under several categories (i.e. ops, programming) and for each skill listed i format them bold, italic, plaintext with a legend showing that those map to adept, proficient, and working knowledge

SuccessFactors HR product used to do this (may still do).

You had to drag and drop your skills within a kind of bell curve. It forced you to prioritise only one or two as your super skills, then a larger number that were your next top skills, and finally a whole bunch of stuff at the lower level.

It worked well, though it was in no way the final word on this kind of very challenging problem.