Ratskinner
Adventurer
Its because that text is not actually as clear as you seem to think. It does not specify that the physical damage is concentrated in a few final HP or evenly distributed amongst them all. For example: "a portion of" is less explicit and clear than "a few of", "some number", or "a portion of each". Applying the idea of a "a portion" to a collection of objects could mean any of those. A portion of 12 cans of soda could mean 3 cans, 3 or 6 cans, or half of each can. Saying "A portion of these twelve points represent actual physical damage." Can equally be read as saying that: "some of the points, but not the others, represent physical damage" or "some fraction of each point is physical damage".
The fact that one can easily imagine other language that does explicitly determine which is the correct reading is telling.
For example, even the sentence: "Every hit point represents combination of both the physical and non-physical proportion of a character's hit points, and therefore a hit always produces some sort of nick, cut or bruise as well as depleting the character's luck, provenance, destiny, prowess and stamina." would make it perfectly clear. Gygax doesn't bother to grace us with such a sentence, and in other places seems to argue the opposite point. In part, this is because he using a lot of confusing and unclear language.
I've got a text document with just about all the official AD&D language (or at least all from Gygax) on HP collected in it (I didn't do the work, and I don't know who did.) I can only tell you one thing for certain: The text resolutely avoids any language that would actually make it explicit how HP are supposed to be treated in this regard. AFAICT, the words "each HP" or "every HP" or "every hit" don't even occur to him to write. In fact, even the quotes that I think lean most heavily in the direction you favor...actually don't, when looked at closely. When he discusses what saving throws mean, it gets particularly unclear. He even gives a Rasputin example which refers to individual HP explicitly as being physical and non-physical, but in other places seems to feel that every hit does at least some physical damage, but doesn't say a minimum of 1 point.
Whether this "fuzziness" is intentional to permit flexible narrative at the possible expense of coherent narrative or not is, I think, unclear. His love of writing in purple prose doesn't help any, either. It makes it more like analyzing Biblical text, and makes it too easy for people to read into it whatever they are predisposed to want to see. My personal suspicion is that he knew that the whole shebang was a hot mess for the narrative end of things, but wanted to keep it for the sake of mechanical simplicity and chose to dress up that decision in flowery language as a distraction. The language necessary to make it explicit is just too readily available for me to believe otherwise.
Some choice Quotes:
HP apparently come in two distinct flavors, physical and non-physical:
"Therefore, let us assume that a character with an 18 constitution will eventually be able to withstand no less than 15 hit points of actual physical damage before being slain, and that perhaps as many as 23 hit points could constitute the physical makeup of a character. The balance of accrued hit points are those which fall into the non-physical areas already detailed. Furthermore, these actual physical hit points would be spread across a large number of levels, starting from a base score... "
Physical Damage is not proportional to HP marked off...:
"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[sic] sustained - at least in proportion to the number of hit points marked off in most cases."
(Bonus points because he doesn't specify in proportion to what....like, does he mean that a 12-point hit doesn't do twice as much physical damage as a 6-point hit? or that a 6 point hit doesn't mean the same thing to a 12 point character as it does to a 100 HP character? Both? Something else?)
...but maybe some of it always is?:
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.
Anyway, there's that.
