Lxqt is the closest to allowing that because it wraps standard tools when possible, but this wrapping of standard tools also means that those tools don't really work.
For example, I use slock for screenlocking, but there is actually no working third party freedesktop screensaver implementation that doesn't tie you into their DE.
Xsecurelock seems to have hacks for it, but it can't even do something as simple as just showing an image without breaking with the wrong window compositor.
I tend to disagree here. I recently switched back to MacOS after years of running both. The DEs on Linux are just one generation behind. Things have gotten better, but macOS and to an extend Windows are ahead.
Linux DEs would be well advised to onboard more graphics and UI experts to make them more user-friendly and stable. Desktop metaphors have more or less stabilized and it's counter-productive to have 5 takes on the Linux-side alone.
The entire problem starts and ends with this term. It is ambiguous, personal, localized, fluid and case-dependent.
What is friendly to one user, is insulting to another. What is friendly to me at 10:00 in the morning is frustrating when I have a presentation in two minutes. What is friendly to an American pensioned welder, is insulting to an Iranian accountant.
Just to explain why I love Linux so much - when I'm in Gnome, I'm not bothered by any alerts or notifications or popups or sounds or ads or anything! It's a silent, stable, good looking desktop that runs my programs and doesn't get in my way at all. It's amazing! I truly love it.
I think Linux DEs are fine, it's just that the default config / on-boarding rarely asks what the user wants and what they need.
More distro/DEs need to incorporate UX/Desktop Layout Switcher, like Ubuntu Budgie, Zorin OS (Gnome, XFCE), Manjaro (Gnome, there are plans to do KDE as well in the forum?), and FerenOS. It'll solve the issues of personal preference in UX, as people could just one-click choose what feels/looks the best for them.
I personally don't mind taking a few hours setting up the UX I want with Fedora KDE, but I doubt most others do.
And that's the problem with the proliferation of DEs. Applications, which range from having no developers actively working on them, to the best teams at Microsoft working on them, have to handle yet another DE, and have to deal with the bugs raised by the users of yet another DE, etc.
UI/UX is hard enough to begin with, but requiring devs to either maintain several UI/UXs, or try and come up with a design that works across the proliferation of DEs is highly counterproductive.
Very few developers actually attempt to do this, on any platform— virtually none, as far as I can tell. It's slightly more common on macOS for developers to actually try to emulate or reuse the design language and look-and-feel of the base system. But on every platform, it's extremely common for GUI apps to just throw the design language and other details of platforms they run on completely out the window. It's the M.O. for the most popular cross-platform toolkit right now (Electron). For every app that maintains multiple UIs, there are at least ten that do that, maybe a hundred!
Besides, COSMIC doesn't use a new graphical toolkit. It uses GTK+, just like GNOME.
But even without them caring for UI/UX, the proliferation of DEs, even with common UI toolkits in the Linux world means they spend a lot of time and energy working on bugs that are not true bugs but are artifacts of a UI theme that the developer did not consider while developing their app.
For example, it's almost certain that the unified tooltip in COSMIC will lead to bugs complaining about how users are unable to drag the window by clicking on the chrome. In this case it would be fairly easy for a dev to close the bug because this is such a prominent and obvious difference in COSMIC. But there will certainly be other UI differences that will not be as easy to pin down to being the result of COSMIC's UI changes, and will not be as easy for devs to close.
Ideally, that's what the freedesktop.org specifications help with. You build against the specs and interfaces, and the code should work across DEs that implement specs from freedesktop.org. In my (albeit limited) experience of writing against freedesktop.org specs, it works pretty well.
Heck, many apps are web-based and uses electron anyways, and those are generally multiplatform anyways.
I think if whatever app they make/port worrks via Flatpak, it should work on all/most modern distro.
Edit: it's GTK so no problem
System76 is only adding to that mess.
Or if they're interoperable. For instance, icewm doesn't have a screensaver of its own, but it just uses xscreensaver so it's fine.
I use KDE now which does provide a lot of choice but I'd love something that has tiling built in. And yeah I know there's add-ons for KDE that do that :)
Edit: this is the one: https://github.com/Bismuth-Forge/bismuth
There's also kwin-tiling https://github.com/kwin-scripts/kwin-tiling
Not sure which is best tbh. I have yet to try them
Guide: https://userbase.kde.org/Tutorials/Using_Other_Window_Manage...
Unpopular opinion, but more DEs is fine and good, especially if they will have teams that are either (a) large or (b) well-funded. Plasma and GNOME are very good, and Unity was actually great to use in its heyday.
Imo what we don't really need more of are the conservative, under-resourced 'classic look and feel' DEs like most of the minor players in the space. Those tend to end up incomplete and ill-performing, and there are already lots of them. I hope the existing ones thrive, but I don't think having more f them would do much good.
But anything as good as the big two, but with a different focus? Let's see it!