The presence of another item in the gameworld, when its attached to an NPC, has no reason to be anything but a single line in config. Another piece of armor doesn't DO anything. It has no physics, no hitbox, no location that isn't defined by its wearer.
That 'single line in the config' is far more important than you're giving it credit for.
That Skyrim is always running a few bytes of RAM away from catastrophe?
It's in the realms of being tenuous, and that's why the PS3 had so many problems after long-play, it became so full of information it ran out of space.
A cell can have hundreds of trees and not crash, but a few extra inventory references spells CTD?
Not one cell in the game has anywhere near hundreds of trees.
I can drag sixty pieces of armor into a scene, and nothing bad will happen. You can spawn hundreds of physics-enabled items in the console, even on my low-end PC, each one requiring more complex calculations than a dozen cuirasses. Consoles can handle this load too, through the Oblivion duping glitch.
And the frame-rate is -and-was appalling, so what's your point? If that happened in normal play, people would be outraged.
Oblivion had just as many NPCs on-screen as Skyrim does, with greaves and briastplates. Two ring slots as well. Why didn't the poor RAM run home to mama?
Because the world was no where near as detailed. Most of it was even procedurally-generated in order to save memory.
Don't forget the grass. Skyrim's countryside is considerably less demanding than Oblivion's. That waist-high thick grass is completely gone. And the speedtree models have barely improved, with less wind animation overall. Only the dungeons have really scaled up the fidelity, with high-poly models everywhere.
This is just ridiculous on so many levels. For one, there is no speedtree, they are full 3d models now.
Your fabrications go so far out on a limb in defense of PR doublespeak that it's almost saddening.
And while not entirely your fault, your attempts at both insults and conceptions about how game rendering works are equally saddening.