If you haven't downloaded the RAWs and taken a look at them, then I encourage you to. Lifting the shadows a couple stops doesn't render the 5D III image unuable, however it does exhibit banding before you even lift three stops. The "utterly unusable" image is the +5 stop 5D III image. Maybe it's not as obvious in the small JPEGs I shared in the first post...but when you see the RAW, I think you will understand.
I think I do understand, but perhaps you don't get my point.
Whatever can be seen from the raw file doesn't matter to non-photographers.. Only the end result matters, in the context where it will be actually used. If it used as a small jpeg in the web, then that's what counts, nothing else.
just from a simple empirical standpoint, the +5 stop 5D III image is....really poor.
Well, if I could have gotten that good results pushing underexposed slide film even just two stops 20 years ago, I would have been ecstatic.
It may be poor in comparison with the state of art, but hardly "really poor", let alone unusable: much worse pictures have been used and are still being used, and are paid good money for. Even totally lost shadow details may not matter if the object of interest is not in the shadows. Most photos are not used to make big prints or anything with artistic intent: often it is enough that the object is recognizable.