[holowoodman]

Tons of stuff aren't in wayland that are actually graphics and window related. Wayland just forgot about it, then later on people realized that their design was far too primitive and simplistic.

DMA buffers, color management and pixel formats, scaling and DPI, image and video capture, tons of keyboard and mouse related things, all initially forgotten, now incompatible extras that are inconsistently implemented, frequently broken and forever in beta/staging/unsupported hell...

[Spivak]

If you mean what Wayland literally calls "staging" it means that compositors should adopt it now, it doesn't mean pre-release. Once multiple compositors implement the protocol it can become stable.

[holowoodman]

Staging still means it is untested because not widely implemented. And still unsupported by the majority of compositors. So basically still unusable.

Also, "can become stable" is a very rare thing. Only a single-digit percentage of staging ever became stable.