As stupid as it sounds, some of it might be because they are emulating MacOS: a few years back, I found it infuriating that when I hit Alt-Tab on MacOS, the window list would appear on the primary monitor, not on the monitor where the mouse cursor was.
I've tried very hard to work with Gnome Shell but there are several essential things that I can't get over. How is it possible that in 2020 a DE doesn't work well on more than 1 monitor? I mean, it works, but not how it should. I won't say anything about the top bar only showing on the primary monitor but if I'm focusing on another monitor and I hit the meta button to see the menu to search for an app or a file I have to check the main monitor.
I could partially fix this with an extension but it's not updated and it won't work with the current Gnome version.
So I had to install Unity, which is unsupported and has some bugs but at least doesn't stop me from doing basic things and doesn't get on my way.
As a linux user is frustrating. I don't understand it. I can't see myself using anything else besides Unity for the foreseable future.