Some distros have editions with a WM (usually i3) as a default, yes. These editions tend to come with some basic config so it’s more usable out of the box. But you can also install WMs side by side with DEs and then switch in the login manager (GDM, SDDM), just the same as you can install multiple DEs on a system. You could also install a headless version of a distro first and then install only the WM and whatever other tools you want on top of that. Basically all system settings can be changed through config files or CLI programs, for some things like audio and bluetooth there are good DE-independent settings programs like pavucontrol.
As for advantages, WMs are usually very keyboard driven, you pretty much never have to touch the mouse. They also tend to be fairly light weight and use little RAM. My favourite i3 feature is that workspaces are per-monitor, so I could easily move multiple windows between monitors and not lose the way they are set up.
As for disadvantages, changing any system settings tends to be a research project, because there is no centralized solution, it’s even worse than Windows in this regard. Personally this is the main reason I switched back to KDE from i3. I could also never get theming to work quite right.
WMs typically do not include stuff like a custom GUI for system settings and do not have a suite of GUI software associated with it (think Kate, Konsole, Dolphin etc) - it is just a piece of software for managing windows, you have to put the rest of the desktop together yourself.
The way I see it, GTK is really a framework for building cross-platform GUI apps. Then handling display server compatibility makes perfect sense to me.
If this was meant to be a dig at Wayland, I’m pretty sure GTK also needs explicit and direct support for X11, Windows and MacOS. It just already exists.
The flipside of this is that you as the BDFL are not in any way entitled to community contributions. If they decide to not like your furry board, they are free to fork the project, but splitting the development efforts could very well kill both projects, so sometimes it is better for the project to listen to the community.
I saw a comment from an nvidia dev somewhere that XWayland support is enough to resolve the flickering, but compositor support is needed for best performance.
Nouveau should have already been fine, this should fix the proprietary driver’s issues. AFAIK this is a core issue of the proprietary driver, so should affect all cards.
I tried Wayland on my 16xx series GPU, Electron apps were only annoying, but games were unplayable. The desktop itself and Wayland native apps worked fine, though.
Well, this is the root cause of this specific issue if you treat nvidia’s part of the stack as some barely changable black box (which is what it is right now). It’s not that I disagree open source drivers would be better, I just already own an nvidia GPU :/