D'karr has the answer here. It has never been part of D&D that hit point loss is nothing but tissue damage...
I've got the 1e DMG. I can quote the relevant text. I'm familiar with 1e mechanics. I believe you are wrong. Hit points loss has always represented more than tissue damage, but it has never been divorced from tissue damage. In other words, each bit of damage has always represented a wound of some sort, but lost hit points incorporate more than just the physical wound - but always at least some physical wound.
The 1e DMG explanation of hit points is well worth reading in full, but for the purposes of this discussion the most important point is this:
"Each hit scored upon the character does only a small amount of 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 six 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 reset and recuperation to regain the physical and metaphysical peak of 95 hit points."
I'm sorry, but speaking quite frankly, your description of how hit points have always been looks NOTHING like hit points have always been, and is a description that became popular only when rationalizes changes to 4e healing mechanics.
- it has always been possible to lose hp to fatigue and exhaustion, for instance. And evading an attack can certainly be fatiguing.
To the extent that I accept that it is possible to lose h.p. to fatigue and exhaustion, it has never been the case that hit points lost to fatigue and exhaustion are both the ordinary hit points that track wounds (instead of say non-lethal damage) AND also represent mere ordinary fatigue in the sense of being 'out of breath'. When a player takes actual damage from fatigue and exhaustion, such as on a forced march, it is not at all clear to me that the reason for the loss of hit points - above and beyond a mere 'fatigued' condition - is not actual tissue damage - blistered feet, bleeding sores, torn muscles, etc. Merely being 'out of breath' as you might get from a non-wounding combat or any other aerobic exercise and being temporarily tired is not hit point damage, because characters recover from that condition far faster than they do from the sort that involves receiving wounds. In point of fact, in 1e forced marches and similar sources of exhaustion weren't modeled by hit point loss, but by (in essence) level drain. And exhaustion was not recovered or cured in the same way or rate as damage from wounds. Simple fatigue unaccompanied by wounds has never been a source of hit point loss.
There are RPGs in which casters can fail to cast their spells. D&D has never been one of them - casting success is automatic.
This is not true. AD&D 1e had a variety of rules for spell failure, they were just generally ignored.