Actually, I think that's pretty relevant to what DEFCON 1 is saying. Basically, what I'm interpreting from his posts is this:
1) The relative potency of game mechanic elements is objective, at least within related categories. A 15th level wizard is more powerful than a 5th level one. An ogre is stronger than a 1st level fighter, but a 10th level fighter is stronger than an ogre.
2) The relative potency of narrative elements is subjective, and can vary from campaign to campaign. If we accept reskinning as viable, there's no strict relation between a narrative object and a game mechanic object until we declare one (usually as part of framing the scene.)
3) Once we add in declarations linking a game mechanic object to a narrative object, we implicitly add a host of constraints to any further declarations. If I define a 1st level fighter as a superior swordsman (and to be clear, this is about the DM and player both accepting this as true, not the player stating a character's belief), then definitionally, common guards and peasants must be assigned stats that would allow the superior swordsman to beat them. They might only have 2 HP, no stat above 12, and no weapon proficiencies, just as an example.
But, once that constraint is assigned, that will certainly have profound implications on how we frame further scenes, especially in regards as to how we assign mechanical opposition. We can't have the town guard show up as 4th level fighters because we've already made a declaration that town guards are inferior swordsmen to this 1st level fighter.
4) Our common fantasy tropes and use of defined stat blocks simply serve to do offload a lot of that decision making for us. That's why the 1st level "greatest swordsman" is so problematic; to maintain consistency, a large swath of our available tools, tropes, and assumptions have to be sidelined. In that game, 6 kobolds can ravage the town guard, and 2 ogres is an existential threat.
This.
It pretty much sums it up how it is to be resolved if we consider D&D being at least partial a Role Playing Game.
To elaborate a bit: There are some DM in whose worlds the heroes with their class levels are in fact the best of the regular folk, no matter if they are level 1 or level 20, they always can even mechanically outpace common folk. For the given RP - scenario : "player is the best swordsman in the world"
these kinds of game worlds are the best, because at any point this always can be proven, even mechanically.
2e had some campaign guide which gave advice on such scenarios fro mthe reverted POV:
Is it possible that player X is a 15th level cleric but only lowest tier in his church? Where his high priest might not even be level 1 but a commoner? Or that a king is only a level 0 commoner, so every fighter can easily take him out?
And the answer is yes that is totally feasible, e.g. the head priest might be a much more devout follower of the PC Xs deity, and the king is determined by birth and not by his levels in fighter or paladin class.
Their tasks are different to those of adventurers, they do not crawl around in the city sewers or some old mine to fight monsters but they lead a church or an empire.
In other worlds, if you would try to emulate every PC view (RP - wise) with a mechanical backbone, you would have to make the high priest of the party cleric be several levels higher etc.