Real physical units make sense when you're printing on paper.
I don't see how they make sense on screens. A one square inch image is fairly large on my phone, not too big on my desktop monitor, and pretty darn small on my tv. That's not to say that pixels make sense to use for layout at those scales either, but before everybody got into high dpi with scaling, it kind of worked... If you were comfortable with tiny text, you ran a higher resolution and if you needed things big, you ran a lower resolution.
Monitors these days provide metadata on their physical size. This laptop screen defines itself as 280x190 mm. Sure, that's not 1:1 with end user distance from screen, but it's a hell of a lot better than switching to mobile layout on my desktop based on how much I zoom my fonts and narrow the window.
> That's not to say that pixels make sense to use for layout at those scales either, but before everybody got into high dpi with scaling, it kind of worked... If you were comfortable with tiny text, you ran a higher resolution and if you needed things big, you ran a lower resolution.
And even with so-called "dpi" scaling, CSS pixels remain that except users have more options to also have their large TV display finer details.
I don't see how they make sense on screens. A one square inch image is fairly large on my phone, not too big on my desktop monitor, and pretty darn small on my tv. That's not to say that pixels make sense to use for layout at those scales either, but before everybody got into high dpi with scaling, it kind of worked... If you were comfortable with tiny text, you ran a higher resolution and if you needed things big, you ran a lower resolution.