By making clients responsible for all of their rendering, Wayland makes it possible for clients to be smarter about things like double-buffering. There are other benefits outside of graphics. It's much easier to sandbox applications, for example.

Is Wayland really better than Xorg?

Even though Wayland eliminates most of the design flaws of the Xorg it has its own issues. In order to communicate with the display server the programs, which act as clients, running on the system must know how to communicate with it. Xorg being older than Wayland is more developed and has better extensibility.

Is Wayland better than X11?

Wayland is also superior when it comes to security. With X11, it's possible to do something known as “keylogging” by allowing any program to exist in the background and read what's happening with other windows open in the X11 area. With Wayland this simply won't happen, as each program works independently.