I am somewhere in between. I don't go for hi-DPI but am using 28" 4K on the desktop and 14" 1080p on my laptops. So identical dot pitch and scaling settings.

I am somewhere in between. I don't go for hi-DPI but am using 28" 4K on the desktop and 14" 1080p on my laptops. So identical dot pitch and scaling settings. I just have more display area for more windows, exactly as you say like a 2x2 seamless array of screens. I actually evolved my office setup from dual 24" 1920x1200 and went to dual 28" 4K. But with the COVID lockdown, I only have one of the same spec monitor at home for several months, and realize that I barely miss the second monitor. I was probably only using 1.25 monitors in practice as the real estate is vast. People who complain that a monitor is too large should stop opening a single window full-screen and discover what it is like to have a windowing system...