So for a more level appropriate level we've got an ogre swinging a greatclub at someone in "chainmail" over padding (chain chosen because it prevents almost all cutting but does little to mitigate blunt force trauma because it's flexible - and a common armour type).
Again, a cherry-picked example to cast the model in the worst possible light. The model isn't specifically designed to cover that specific scenario, though. Detailing every possible interaction would be boring and tedious, for very little benefit. Instead, we have a streamlined model that works in the vast majority of cases, with a minimum of fuss. (And which suffers from a couple of nit-picky corner-case problems, if you really want to obsess over minutiae.)
A substantive hit with a maul might not kill someone - but it will break limbs or ribs and out the target out of action. A hit by a cutting weapon into metal armour that actually takes effect (which it mostly does by avoiding the metal parts) is likely to at the very least mangle whatever it hits, cutting right to the bone and probably breaking that.
We're not trying to model a substantive hit with an edged weapon that bypasses armor, though. Getting hit by an axe, with no armor (or other factors, like magic) to mitigate it, cannot reasonably result in anything other than serious injury. It's only the existence of armor (or magic) which provides the necessary room for reasonable doubt.
If you're one of the untiring robots of AD&D the only advantage the amateur has is that it will take fewer hits for the amateur to drop the tired professional. And the professional is going to take exactly as long to drop the amateur regardless of how much of a battering they have taken.
And what's wrong with that model? It will get us to the same end-point, either way, but with significantly less math required. One of the major reasons why death spirals are pointless is because they tend to cancel each other out, as often as not. Even if we were modeling pain and bruises and slowed reaction times, the pro is going to even that out as soon as they get a good hit in.
Meanwhile if the professional has had time to rest and recover they are going to have had time to spend hit dice/healing surges, and they are going to have recovered their second wind (both editions) and either their action surge or their encounter powers. They aren't at full capacity yet - but having been given time to recover most of their offense and at least some of their endurance is back even if they have a lot less in the tank long term.
Aside from Daily powers, a fighter who spends hit dice or healing surges to recover
is operating at full capacity for the duration of the second fight.
Everything that happened to them as a result of the first fight is wiped clean. It doesn't matter whether they were literally one good hit away from unconsciousness, because five minutes (or an hour) later, they may as well have been resting in Tahiti for three months. And that completely trivializes the fact that they were hit in the first place. Once those HP are back, the fact that they were ever gone is entirely irrelevant. (It might theoretically matter around the fourth fight of the same day, or the next morning after six fights in one day, but it's entirely irrelevant
now; and it will only ever become relevant for five minutes at the end of the day.)
The fundamental problem underlying this whole debate is that it's all-or-nothing. Each edition only has one set of rules for healing, without regard for the circumstances in which the HP were lost. If (for the sake of argument) we take for granted that HP totals include both physical toughness, as well as fatigue and other factors; then a rule that makes sense in the context of a physical hit does not make sense in the context of a near miss, and vice versa.
The only way to make sense of the unified healing rules it is to go with one extreme or the other - either every hit is physical or none of them are. Either a tough-enough warrior can take quite a number of substantive physical hits before falling, or nobody can stay up through
any number of substantive physical hits regardless of how tough they're supposed to be.
And while it's possible to have a serious world where a number of specific heroes are effectively Made of Iron, it is not really possible to take a world seriously when every single person living there is Made of Plasticine.