Really? I mostly remember it being a 3e thing. Commoner railgun and tippyverse.Shhhh, That model is a kind of sacred cow that originated from Gygax era I guess.
You should treat her with respect!
You can, however, see a connection between some NPCs and PC levels. The knight and vetersn, for example.Very interesting. But to me one of the base assumptions is... wrong. This sheet again (like all the ones for previous editions) assume that specialists have class levels. Which pretty much goes against a core 5E assumption.
In my worlds; kings, sages, soldiers, generals, etc do not have levels. They might have traits and abilities from various classes, but I don't build them with levels as a PC would. For one, hit points would be totally inconsistent with challenge ratings and usability. In my worlds, only the PCs and a few other groups of adventurers do I build with levels. Everything else is built as an NPC, often using the examples from sources and then adjusted with HP, AC, items, and abilities/traits.