Ah, but saving the state of things has nothing to do with graphics. The GPU only draws what actually exists, the moment you leave the immediate vicinity of the body it's no longer there, and thus the GPU doesn't give a damn.
True, but with everything resetting in a game like GTA or RDR you can literally stay in one place and continuously kill everything. Eventually the stuff will disappear even when you are right there with it, and will always hard reset around a corner, meaning you kill 100 things in Area X, go to Area Y and back to Area X it looks entirely normal. With the game remembering the location of everything if you do that in Skyrim everything is still there so any lag from GPU strain is still going to be present anytime you go in that area until it hard resets a few game days later.
I guess the only comparable thing I can say is in Oblivion I could get 10000 arrows through duping, go into a building, and duplicate a single apple. The game would try and render all 10000 apples being loaded at once, which would cause a crash. But if I did it then immediately used the door and exited the cell before the game tried to render everything (in that first bit of lag while it is trying to load the items), I could play as normal. But until that cell reset, any time I tried to go back there it would try and load the 10000 apples again. In GTA or RDR not only do things begin to disappear long before that point, exiting the area and returning would hard reset the area so anything causing lag (10000 apples in this case) would be gone immediately.