Switching desktop environments on Linux is absolutely trivial and doesn't require a reinstall though (at least in my experience of switching from GNOME to KDE on Ubuntu, which took a couple of minutes to pull down the KDE packages and then logging out and picking Plasma from a dropdown in the login screen - and if I feel like it I can switch back to GNOME anytime).
It's not trivial. Just installing KDE packages on a GNOME install will work and is quite easy, but will lead to some mix / subtle setting issues, it's less clean than just a brand new install.
Installing and running KDE will mess up GTK settings in GNOME for instance. You might end up with the Breeze GTK theme in the GNOME session. Which works, but this is most likely not wanted (even though GNOME looks great with the Breeze theme).
I'd not advise regular users to do this without a warning.
I haven't seen this on my Linux laptop, but TBH some UI elements in GNOME look so weird in Ubuntu 24 that I'm not sure if it's broken or intended (but already did before installing KDE).
Trivial to who? A seasoned Linux nerd? Maybe. A regular, non-tech person? Nope. And that is why there is no year of the linux desktop. And if you expect a regular, non-tech person to be able to master the terminal and type in commands you're delusional.
Trivial in the sense of googling "how to install KDE on Ubuntu", picking a result that looks somewhat recent, and following those steps. It ends up being a handful terminal commands which shouldn't be too hard for anybody who has used a keyboard before. That's how I did it at least. There might be more UI centric options.
Also, trying to chase the elusive 'casual user' is what caused all the GNOME UX mess in the first place I guess. I'm not an 'archetypical' Linux nerd, I hate wasting time with fixing stuff that should "just work", but I'm also expecting a computer to be a professional tool which I can customize to my needs (within reason at least).
Windows is not better at this. Plenty of troubleshooting advice says "Now open the registry editor and..." or "Now open this .ini file and..." or "Now open cmd in admin mode and..."
The ease of the GUI ends when a serious system-level issue arises. This has never not been the case, it's just a matter of how much the documentation expects you to know what's going on, and how much that impacts the first-run experience. If the first-run is good enough, "reinstall" becomes the go-to fix.
I wouldn't expect a non-tech person to even understand the difference between an operating system and a desktop environment and why you can switch the latter while keeping the former. Nor would I expect them to care.
