Yeah, that’s a bit of an odd way to write it. I guess it’s intended to be easy to compare to 16:9, 21:9, etc.

2:1 phones already exist. If you're set on an unreasonably large diagonal, the extreme ratio helps, by making the phone thinner (left to right) than it would be with a normal ratio and the same size diagonal.

It'd be even nicer if they'd do reasonably sized phones, though.