Or, "This screen is 7:3" -> ahh, I see, it's almost twice as wide as 4:3!"

Why do you need a "frame of reference" anyway? Reference to what? The only reference you need is the width to height ratio. Which 7:3 expresses better that 21:9.

Things like "18:9" are even more ridiculous. Not only is it 2:1, but also... why 18:9? Why take the shorter side as the "reference"? Why not more logical 16:8? Could it be because, to the simpletons, 18:9 sounds like something has been "added", whilst 16:8 sounds like something has been "taken away"? In other words, nothing more than a marketing con?

All this talking about "reference" means that you, too, have fallen victim to it. Howgh!