That being said, I'd imagine the active circuitry required to capture and process the images in realtime (or 30fps, in this case) is expensive and bulkier than what's currently used. Processing stereoscopic 2048x2048 HDR streams is no easy task, you'd basically be looking at a VR helmet once you consider where to put battery and compute unit.
It's a cool invention, but probably one of those "analog computer" ideas that's harder to scale/apply than the cheaper alternatives.
And any processing bulk could be belt worn or even sitting on the ground connected by a cable: you're already tethered to the welder and buffer gas tank after all!
But there are real, and pratical use cases out there done by smaller companies in specialized fields. The issue lies in creating something with mainstream appeal, which I do agree with you, that's a whole other story.
It wasn't totally clear, but it looks like Mount Sinai might be using Microsoft hololens.
It does seem like John Hopkins has something interesting.
I am not saying it is impossible, but I certainly would not say I was "surprised" Miller welding has not developed full AR glasses for welding. AR is hard and this is early days.