If I remember correctly Linus uses i3 primarily, so instead of wasting 20% of the screen on UI and compensating with a second screen you only look at 30% of the time, it just tiles your windows so you can make more efficient use of the screen you have
Actually, I haven't gotten around to trying Wayland yet! Mostly because i3 on X11 works well enough for me already.
I mean, I literally just plugged in my monitor, then went into Arandr and dragged the funny rectangles a little.
Edit: For reference, my multi-monitor setup is literally just 2 monitors side by side. In my case, I did have to change some settings, specifically set the left one as primary rather than the right one, and make them tile in a slightly different way. But I wouldn't say it involved any "jank" — just some configuration, same as it would on any other OS. (Specifically, I dual-boot windows 10 for some rather silly reasons, and I found the multi-monitor configuration process very comparable in terms of jank or complexity.)
This is completely untrue in my experience. My X230T has two battlestations: One with an old, square Samsung VGA monitor, and another two hours away with a modern, DisplayPort, high resolution Dell. I regularly hot-swap monitors by unceremoniously pulling it off or slamming it on to either docking station while it's running, and even transform it into tablet mode and flip the internal display output 180° without upsetting the external display.
All of this on Fedora 38 Cinnamon, firmly running X11. No "jank" in sight.
I mean X11 is a janky mess. Wayland adds a lot of improvements (I can finally do screen-based scaling with logging out!). The software support on DE side is just missing a bit (Tho it has gotten leaps better in the last 5 years, I am now using KDE in wayland mode with an intel iGPU without issues! Hussah!)