Yet many of us have been quite happy with it for decades, and the major problems tend to be with new stuff that seems to be added just to do something different.
I would say that in addition to a usable desktop, Linux distributions generally also provide a more stable Windows environment than Windows itself does. I have quite a suite of games in Steam and GoG, and I find that many older games that simply cannot be coaxed into running on Windows can be made to run happily on one version of Wine/Proton or another.
There are still some weak areas in desktop Linux if you're running a desktop that isn't Gnome or Plasma - wifi configuration comes to mind immediately, as does sound configuration. Bluetooth can be picky if you don't know to get all the non-free firmware.
But really, we're living in a dream era of Linux desktops, if you happen to have lived through the early days of `startx` and XFree86. Hands up if you ever smoked a monitor coil with a bad X config file...
Recently I needed to switch to Wayland due to my monitors setup. Then I also needed to write a small program that capture application screen, which is a stupidly simple thing to do on Windows, Mac, or even on Xorg. For Wayland I had to jump through bunch of stupid hoops just to get it kinda working ...
I had no resistance from my corporate overlords over this. I get my work done and I'm more effective as a developer.
The corporate MS apps all work in a browser. I don't use any of the office apps for anything serious.
The Linux desktop is here already and is accepted. Also KDE is quite nice and snappy most of the time.
When I first started using Linux, there was no kernel modesetting and XFree86 ran as root. I had to manually configure my graphics and display settings by editing the Xorg.conf in nano, or sometimes I could get YaST to do it. Multi-head output was not well-supported, and you often had to restart to reconfigure your outputs. Installing the NVIDIA driver was a straight up pain in the ass. (Some things never change.) X.Org eventually improved and added hotplugging. The Linux desktop stack went through a lot of "new stuff" like new versions of DRM/DRI, the addition of hotplugging, the introduction of KMS and libinput. Dynamic input configuration was added with the `xinput` command. The XInput2 extension was developed to greatly improve touch and pen tablet support. XRandr made it possible to dynamically arrange displays, replacing Xinerama. UI toolkits needed to be rewritten to support scalable rendering so that we could have high DPI support. Most recently, a lot of work and many new protocols across multiple parts of the desktop stack had to be re-hauled from kernel to userland to support explicit synchronization for graphics tasks and buffers. All of this required major shifts, and that broke user's workflows at some points. Plenty of people were broken by the gradual transition to using libinput, from graphics tablets to Synaptics touchpads, a lot of work had to be redone in order to re-haul the input system. Only recently are there Linux laptops where the out-of-the-box touchpad experience is good enough to rival a MacBook, and it's certainly not all of them.
Don't get me wrong, I loved KDE 3. And despite all of it's flaws, I still prefer Linux greatly over the other options available. But would I go back to using Linux 2.6 and KDE 3 and etc. today? Fuck no, we've improved so many things since then. And yes, no question that at times things have felt like they've been moving backwards in some regards, but it really isn't for nothing. The fact that modern desktop Linux trivially hotplugs displays with different DPIs and refresh rates (and potentially variable refresh rates) is genuinely something that took a herculean effort. All of that work required massive rewrites. It required kernel changes, graphics driver changes, it required major UI toolkit changes, it required redesigning apps and rewriting components.
And yes, I admit I am not the biggest contributor to open source or anything, my patches are mostly unimportant. But, when I hit something that sucks in the Linux desktop, I do try my best to see if I can't do something about it. I have contributed random little bits here and there to various projects I care about. Most recently, I've been doing work to improve some situations where thumbnails in KDE are suboptimal. There's easily thousands of these little small issues that make Linux worse to use on desktop, we've got plenty of work to do.
And I make it work. Except for work-owned computers, all of my machines run Linux, and I have a fair number of them. I do not have a single box I own personally that boots any other kernel or any other desktop. I know my way around Wine, even enough to make occasional, if small, code contributions. (For example, I made a quick patch when graphics tablets were not working in Wine under XWayland.) So I'm not suggesting that it's unusable, but I can't recommend the Linux desktop to random people. It's been getting closer, but a lot of the reason it's getting closer is because of some of the efforts that I assume you'd complain about.
Only issues I can think of that have every affected me were pulseaudio related.