I agree with most of your post but not this bit, nvidia cards tend to run cooler/throttle at lower temps, I'm also pretty sure they have lower RMA % than AMD as well, this was discussed a while ago on here before the real mining craze hit.
They may run cooler/throttle at lower temps and may have slightly lower RMA % don't know if this is true but just humbling what your saying however Nvidia cards are not used for mining where a vast amount of inexperienced people are jumping on the bandwagon and trying to make profit and don't have much idea of air flow and how the cards work in terms of keeping cool.
So my point was if Nvidia cards were just as capable or better as AMD cards at mining they would suffer the same fate from these inexperienced people as obviously people would be using NVidia cards too. Doesn't matter if they run slightly cooler they will still burn if not set up right as it sat right next to each other where minimal air reaches them.