Wayland does address basically all of the tearing problems assuming a correct GPU driver (all of the opensource ones). There are several different problems, all of which are solved:

- Clients only provide complete buffer updates rather than drawing on to the front buffer, fixing tearing for all non-OpenGL apps

- Each monitor can have its own set of buffers and sync signal (technically the wayland protocol doesn't specify this, but makes it possible, and Weston does it correctly)