Swivel/tilt/pivot and multi-monitor brackets make for great flexibility, though. I've seen setups with a 4K monitor flanked by two smaller vertically oriented screens. Or you could stack monitors on top of each other, or a combination.
The biggest setup I've seen at a desk was six 4K monitors, arranged three wide and two tall. When you've got a lot of monitoring to show at once...
all this 1x1 and 4:3 business just sounds like hipster nostalgia to me. granted I'm not a programmer, but we're not all programmers either. it's almost as if there's some virtue signaling going on there. oh the desire to be different in a mass produced world.
Two windows side by side on 1280x1024 are 640 pixels wide each, on 1920x1080 three windows are the exact same width each, plus you get an additional 56 pixels of vertical resolution, so in fact more lines of text.
And of course once you go to 2560x1440 or 3840x2160, you either get oodles of space or sharper text, thanks to display scaling.
I run my 4K 27" desktop monitor at 150% scaling, and usually snap two windows side by side, sometimes up to four windows with corner snapping. It's like having two portrait mode monitors side by side.
On my laptop, the 1366x768 screen lacks the resolution to do this. Vertical resolution is the key, no matter the form factor.