Magnesium is fussy stuff and needs to be a special alloy with other materials to die cast well. That barrier was broken in the 80's. But what you almost entirely see today are lower quality softer aluminum-magnesium alloys which aren't very durable.
I don't think I'd want a camera made out of that, since there are better options.
I like the titanium hardware on my Ebony camera. But no way I'd be a sucker for such and such a marginally useful camera made of it. I'm an actual user, not someone looking for a conspicuous consumption fireplace mantle conversation piece next to the silver DeLorean parked on the rug.
My 8x10 is the original Phillips design (serial no. 009, in fact). He was the first to use custom plys, in this case, fiberglass bonded to veneers or expoxy-impregnated cherrywood. Now carbon fiber to wood plys have entered the scene and make lot of sense.
Durable, rigid, lightweight, and better thermal insulators than metal. And simply too light of a view camera is basically a kite in a breeze. You need some kind of sensible balance.
There have been aluminum monorail 4x5's clear down to 2-1/2 lbs, like Gowland and Toho. And some non-folding wooden models are nearly as light.