The Crimson Binome
Hero
I think you haven't actually read that passage, at least not recently. Gygax doesn't talk about damage. He talks about Hit Points - your capacity to withstand damage.It still contradicts your claim. Even as far back as 1e, most of the damage was non-physical, which means invisible. A bruise for 10 out of 100 hit points is the same as a bruise for 1 out of 10 hit points. 10% is 10%. Heck, Gygax gave an example of how many hit points were meat. He listed the meat hit point going up to a max of 23 at 7th level. That meant a fighter with 60 hit points at 7th level had 37 non-meat hit points to lose. Good luck seeing those.
What he said is that your starting amount of HP (and any bonus HP gained from having a high Con score) mostly reflected your physical health, and that most of the HP gained by a high-level character represent increased skill and luck and divine favor and magical wards and so on.
That doesn't mean you can take 90 damage without it making a leaving a mark on you. That interpretation would be ridiculous, since it would require meta-gaming to address. If you choose to use such a ridiculous interpretation, then that's on you; I won't defend you from your own foolishness. Even if you just use the proportional model, though, that interpretation is sufficient to say that every loss of HP has a physical sign which can be addressed by the character, and is still perfectly consistent with Gary's statement.