You got me curious, so I looked it up:

  Transports
  
  To date all known Wayland implementations work over a
  Unix domain  socket. This is used for one reason in
  particular: file descriptor messages. Unix sockets are
  the most practical transport capable of transferring file
  descriptors between processes, and this is necessary for
  large data transfers (keymaps, pixel buffers, and
  clipboard contents being the main use-cases). In theory,
  a different transport (e.g. TCP) is possible, but someone
  would have to figure out an alternative way of
  transferring bulk data.

So, that is why I hear about needing X11 compat for remote connections; wayland connections are still sockets (not e.g. shared mem), but they require the ability to pass file descriptors through the socket, which can only be done with Unix sockets. (and those file descriptors provide access to shared mem)

I don't see any details about how this interacts with OpenGL, like whether indirect rendering is possible or if applications would need /dev mounted.