Directly using physical PPI has basically never taken off anywhere. Everyone is using "arbitrary 1x" because designers and developers have never started using p

Directly using physical PPI has basically never taken off anywhere. Everyone is using "arbitrary 1x" because designers and developers have never started using physical dimensions for digital UI elements. Most people speak in "96-dpi-ish logical pixels" because it's much more convenient. Everyone knows what 128px approximately looks like. No one measures UI elements with a physical ruler in millimeters.