The GNOME redesign. The old 2D GNOME was OK. It was functional, stable and pretty (for someone who thinks that Windows 3.11 style is a good fit for a work environment). Then the old software was abandoned and the update was pushed onto users.
KDE also had a transition disaster. That time was not a good time for Linux on the Desktop.
KDE's transition disaster came a bit earlier, with the release of KDE 4.0 in 2008. By the time GNOME 3 came out in 2011, KDE 4.x had seen 6 or 7 feature releases, and had (imo) largely recovered from all the rewrites in terms of feature parity. I was pretty happy on KDE in 2011.
I'd say UbuntuMATE is functional, boring and pretty, and frankly should be the modern standard for a work environment linux.
For me, it's the Windows desktop at work. I'm accustomed to Windows spawning windows fully or partially out of bounds, though at least that's something that you can fix with the "Move" option from the Ctrl+Space menu. But for a few weeks now, there seems to be a bug where the affected window just stops being rendered entirely. It's in the taskbar, I can start Ctrl+Space "Move" and see the movement cursor, but there's nothing there. I don't know what triggers it yet.
Meanwhile, my Linux desktop has no problems at all.
Linux package management alone puts it ahead of both Windows and OSX in my book.
Having said that, Pop!_OS was also problem free for me for quite a while until the desktop blanking issue started happening - right at the time of NVIDIA driver upgrade. Linus was right shitting on them - my next laptop would not be using NVIDIA for sure.
Close to two decades of using Linux desktop on a daily basis and I still have to deal with these issues. As someone who doesn't have any intention to leave Linux due to these issues, I don't think there EVER will be a 100% rock-solid time for Linux desktop. Wayland will stabilize and then people will point out issues with it, come-up with another component and we will wait for that to stabilize - and on and on, forever.
Ironically, such issues rarely happened, if ever, when I was using Ubuntu Dapper Drake.
Are you sure you aren't having power issues? I had similar problems I think I fixed with randr, but a UPS for your monitors might be a better choice. Never daily though, more storm based or once every few months.
We had a solid 10 years of Apple neglecting OSX and more importantly Microsoft ruining windows with their tiles dual desktop. What did Linux do? pointless rewrites that added nothing to the fundamental usability of the desktops.
The opportunity has passed. We either hope that Satella moves Windows closer to Linux/Unix, or ... desktop linux fades with desktops in general.
The challenge is that Linux isn't a singular product its a source compatible ecosystem of parts. There has always existed a collection of excellent parts one could use to make an excellent experience. However as a user you probably don't want to build your own distro so you are going to be relying on someone else's collection and projects come and go and differ substantially in quality both between projects and over time.
For instance Ubuntu has basically from my perspective gone to hell.
I can see why existing Linux users may have resisted the change but I wouldn't have even tried Ubuntu long enoughto switch to Linux had they stuck with the old system.
Windows 3.11 is a terrible fit for productivity, Win95/98/2000 were immensely better. The Windows usability only improved until mscursed themselves with Windows 8 (with the exception of Vista which was released before it was done and was almost as buggy as modern Linux, though SP1 fixed most of that).
For instance KDE 4.0 which wasn't really ready came out 11 January 2008. Fedora 9 came out in May.
Had simply choosing 3 or 4 beta as it might accurately have been called been possible at login I think there would have been zero issues. 4.0 wasn't actively broken but it lacked polish and it was missing features from 3.x that hasn't been implemented yet.