They changed a little in 2e. In 1e it was very clear, but 2e didn't go into the same detail or have anything like the same care spent on a fundamentally weird mechanic. But it's 2e that's the outlier here.
I disagree; I think that what you quoted backs up my point very well. Let's read these quotes again, but change where you've placed the emphasis.
Originally Posted by AD&D 1e DMG, page 61
As has been detailed, hit points are not actually a measure of physical damage, by and large, as far as characters (and some other creatures as well) are concerned.
First, the fact that he says "by and large" is clearly indicating that his previous statement is not meant to be understood as an expressly literal definition; "by and large" means that there's a degree of flexibility.
What's more striking is that he's saying "as far as characters...are concerned." This is clearly him saying that hit points are a dissociated mechanic, as creatures don't have any conception of it (because, as he talks about more clearly later, the issue of damage scaling is too great for him to ignore).
Originally Posted by AD&D 1e DMG, page 61
Damage scored to characters or certain monsters is actually not substantially physical - a mere nick or scratch until the last handful of hit points are considered - it is a matter of wearing away the endurance, the luck, the magical protections.
The first part of the emboldened areas shows that he is clearly saying that some degree of physical damage is being taken; he's simply saying it's scaled down to being "a mere nick or scratch."
The second part is his definition of why these physical wounds are so slight, despite the numbers; hits are still being landed, they're just not that large (this would later come to be called "rolling with the blows" - which is still incumbent on blows being landed to roll with).
Originally Posted by AD&D 1e DMG, page 81
For those who wonder why poison does either killing damage (usually) or no harm whatsoever, recall the justification for character hit points. That is, damage is not octually sustained[ - at least in proportion to the number of hit points marked off in most cases.
Notice the emboldened part here; it clearly indicates that damage is being sustained, just not in proportion to the hit points marked off - damage scaling again.
Originally Posted by AD&D 1e DMG, p.82
It is quite unreasonable to assume that as a character gains levels of ability in his or her class that a corresponding gain in actual ability to sustain physical damage takes place. It is preposterous to state such an assumption, for if we are to assume that a man is killed by a sword thrust which does 4 hit points of damage, we must similarly assume that a hero could, on the average, withstand five such thrusts before being slain! [Why then the increase in hit points? Because these reflect both the actual physical ability of the character to withstand damage - as indicated by constitution bonuses- and a commensurate increase in such areas as skill in combat and similar life-or-death situations, the "sixth sense" which warns the individual of some otherwise unforeseen events, sheer luck, and the fantastic provisions of magical protections and/or divine protection. Therefore, constitution affects both actual ability to withstand physical punishment hit points (physique) and the immeasurable areas which involve the sixth sense and luck (fitness).
Here Gary out-and-out says that increased hit points reflect the ability to withstand greater damage. He also talks about the "sixth sense," but doesn't say specifically what it relates to beyond increased hit points, which I believe talks about the issue of damage scaling (hence why he'd mentioned it so many times previously, and does again later).
Originally Posted by AD&D 1e DMG, p.82
Consider a character who is a 10th level fighter with an 18 constitution. This character would have an average of 5% hit points per die, plus a constitution bonus of 4 hit points, per level, or 95 hit points! Each hit scored upon the character does only a small amount of actual physical harm - the sword thrust that would have run a 1st level fighter through the heart merely grazes the character due to the fighter's exceptional skill, luck, and sixth sense ability which caused movement to avoid the attack at just the right moment. However, having sustained 40 or 50 hit points of damage, our lordly fighter will be covered with a number of nicks, scratches, cuts and bruises. It will require a long period of rest and recuperation to regain the physical and metaphysical peak of 95 hit points.
There's no need to change what you emboldened here, since it out and out says it still grazes the fighter - physical damage again.
Originally Posted by 3.5 SRD
(and unsurprisingly identical to the PF SRD)
What Hit Points Represent
Hit points mean two things in the game world: the ability to take physical punishment and keep going, and the ability to turn a serious blow into a less serious one.
Again, this highlights my original point - the blow has been landed; the degree of seriousness is a scaling issue, but doesn't negate the fact that hit point loss represents being struck in combat.
Simply put, I find there to be no support at all for hit points being anything other than physical wounds, at least in any edition of the game prior to 4E. Virtually all of the cited examples are simply trying to address the issue of why a set amount of damage is lethal to low-level characters yet inconsequential to high-level characters, when levels themselves are a dissociated mechanic. In other words, they were trying to address damage scaling, and in the process ended up creating a lot of confusion.
I can see why people would think the text was saying that hit point loss isn't a physical wound, but I don't believe that's what the text is saying or is attempting to say.
