I have my comp in a small nook in the side of my bedroom that's supposed to be where a dresser lives. Couldn't fit two monitors side by side easily so I put two ultrawides, one on top of the other. Works out really nice tbh.
I have never seen a setup like that personally, so it feels weird to me. But I feel like it would be hard to allways look up to your second screen, because that one wouldn't be on eye hight. And it sounds pretty anoying when you want to drag ans drop your windows by holding them an the top of your screen.
But I get that it has advantages like less space used. Probably mostly feels weird to me, because I don't know it :)
That's a valid point, I'll probably explain why I like it.
I don't look up, I look down for the second and primary is eye height. I'm on Linux with KDE which has a nice 10px boundary before passing onto the next screen so I can snap all I want. I can also snap on my top bar which has the launcher, taskbar and stuff.
I can access my bar from both the top and the bottom which is nice and convenient. Here's a picture of the insanity :)
Back when native resolution was 4:3 it made more sense to have them side by side, but 16:9 it just makes more sense to have them vertically stacked.
Also, my setup is a 50" 4k TV for the top screen and a 43" 1080p for the bottom, I'd have to look sooo faaar over to see the other screen that I honestly don't have the wall space in my room for it. I am generally reclined on a couch while using it, my head resting is centered on the upper screen with either a reference of whatever I'm working on the lower, though usually it will be a twitch stream I'm tangentially interested in but only need to take a look at it on occasion if I head something interesting happening.