The biggest thing for me is that a lot of them don’t officially support dual-booting on one disk, e.g. Kinoite. I like to have multiple distros installed so I have a fall-back. I love using Tumbleweed for gaming, but I’d love to use an atomic distro for my development work. But I don’t want to use one in an unsupported way, as that defeats the point in my eyes.

Also XWayland has many limitations as X11 does.

If an app has only ever supported X11, then it probably doesn’t care about those limitations (the apps that do care probably already have a Wayland version). And if an app doesn’t care about the extra stuff Wayland has to offer, then there’s not really a reason to add the extra support burden of Wayland. As long as they work fine in XWayland, I think a lot of apps won’t switch over until X11 support starts dropping from their toolkit, and they’ll just go straight to Wayland-only.

will not solve issues with compositors not having it

Many compositors already have patches for explicit sync which should get merged fairly quickly.

graphical libraries not having it

Both Vulkan and OpenGL have support for explicit sync

apps not supporting it

Apps don’t need to support it, they just need to use Vulkan and OpenGL, and they will handle it.

Wayland doesn’t implement sync of any kind, they probably meant to say “the Wayland stack”

Wayland has a protocol specifically for explicit sync, it’s as much a part of Wayland as pretty much anything else that’s part of Wayland.

Nvidia is not the only driver that needs to implement explicit sync.

Mesa has already merged explicit sync support.