There is no de-facto Wayland software like there is the X.org server. Wayland is just a protocol—KDE and GNOME (through Mutter) both implement it. The author is

There is no de-facto Wayland software like there is the X.org server. Wayland is just a protocol—KDE and GNOME (through Mutter) both implement it. The author is saying that KDE did so better than GNOME.