> But assuming they did work on physical inches, they still wouldn't capture how close the device was going to be to your face At least the inch is a unit whos

> But assuming they did work on physical inches, they still wouldn't capture how close the device was going to be to your face At least the inch is a unit whose physical size, by the name, you could assume to not change when screen resolution changes. And also, DPI (or just the physical monitor size) is usually something the user can configure in the operating system - to account for viewing distance or personal preferences.