Here we go again. IMHO, we need a new unit to unambiguously describe angular measure. But also we need to start demanding resolution independent units that map to real world measurements as well.
FWIW, you'd need some profile spec to constrain the problem of what eyeball distance you're looking from. One approach might be to define profiles for desktop, mobile, and projector distances. Is it meant to be accurate? No. But it can stop people from trying to munge angular measures with distance measures.
> we need a new unit to unambiguously describe angular measure.
That's a nonsense unit. You'd need to know where my eyeballs are and change the measure as I move my head around! What happens if two people are looking at the screen?
> we need to start demanding resolution independent units
That's what CSS pixels are. A pixel is 0.26 mm, period.
Right but that's just "for lower-resolution devices", i.e. devices with a resolution lower than the reference pixel. There's no use demanding to have units of measure which the device is incapable of displaying! What possible use would it serve?
https://news.ycombinator.com/item?id=4236429