Uh, it was a long list of things (seven of them) specifically pertaining to high level. Going back to the ones you covered in your initial response:
None of those struck me as being particularly focused on high-level areas of game-play. They seemed low-mid level, or universal (e.g. regardless of level).
Why are you better able to do this at high levels, rather than low levels. Whatever stat covers your ability to know exactly how to do that, a first level character can have a higher stat in that thing than the 20th level character, and yet the first level character is certain death while the 20th level one is certain life. How does that make sense?
It makes sense because the stat in question is hit points. Asking why a character is better able to move in such a way as to minimize damage from a fall at higher level is like asking why they're better able to move to minimize damage from sword strikes at higher level - their greater hit points represent greater ability to reduce damage where "rolling with the blows" can possibly be construed as a factor.
See below on acid trap, and it's even more absurd given I said the dragon rolled a ciritical hit so we know for sure it's the best hit the dragon can do. If HP covers your ability to dodge, it makes no sense.
It's not solely a question of how good the dragon's hit is - your hit points play a factor in characterizing the damage. A critical hit for the same amount of damage when you're at 1 hit point will be completely different because now you can't react in such a way so as to ameliorate the extent to which you're injured...and so it kills you. It makes perfect sense.
The alternative is that the dragon criticals you, and despite having taken what you characterized as massive physical damage, you can then "spend a healing surge" to spike-heal that damage and be completely fine. Talk about making no sense!
D&D is a wuxia/action movie - the PCs are all John McClanes. It's not supposed to be a model for realistic combat, and nobody is saying it is.
Wait, now agility is linked to hit points in this theory? So a character with a 25 dex and a character with a 3 dex both "move quickly enough" to dodge most of the acid (or the dragon's critical hit), in a way they could not "move quickly enough" at first level? The first level character with a 20 dex was unable to "move quickly enough" but the 3 dex guy at high levels could? That makes no sense.
It makes perfect sense, you're just mischaracterizing it. "Rolling with the blows" is your ability to absorb a hit in a less damaging way, which including moving so that it hits a less vital area. Having that be divorced from Dexterity makes just as much sense as having your force of personality (Charisma) have no impact on your ability to fight off magical mind-control (Will save). Is that an imperfect representation? Maybe, but again, it's so minor that it's not anywhere close to being a deal-breaker for anyone who doesn't demand total fidelity to reality.
Remember, this is contrasted with the idea of an acid trap hitting you, and apparently just demoralizing you, since a warlord can then chew you out and you're back at full hit points. Which makes less sense?
Some deal hit point damage and, as this is a discussion of hit points, I think it's pretty obvious those are the ones I mean. So, let's talk about those.
I don't recall any poison or disease in 3E that dealt hit point damage. Maybe there were in older editions (I don't recall, and don't have my books with me), but that would make it pretty clear why those were changed when 3E came out.