[nine_k]

My vision is far from 20/20, and I have trouble discerning road signs at a distance, but I can see how pixels are square on most 24" FHD displays.

For development, a lot depends on the quality of font antialiasing and hinting, though; Linux used to provide superb font rendering in this regard.

[namibj]

I too don't have too good vision, but the 1080p 15" and the 2160p 39.5" at slighly higher distance are just at the point where I don't need High-DPI technology. Seeing pixels at 24" is not that hard. There are screens with significantly higher linear resolution.