Earlier quoted context omitted.
In short: X.org is a decade old display server that became the standard to display graphical window on the majority of Linux distribution. GNOME, KDE, XFCE and others are/were client to this display server. Wayland is a new protocol where the window manager (ie GNOME, KDE,...) is responsible of directly managing the display. Each window manager must reimplement this protocol (or use a library already doing this work)…
It is perhaps worth noting that while X.org is about a decade old, it is an implementation of the X Window System protocol which dates back to the mid 80s. Suffice to say, quite a lot has changed in computer graphics/interfaces since that time, and most modern *nix operating systems end up circumventing quite a lot of X to offer modern features. Thus X brings quite a lot of legacy debt to the table which can't be eas…
However NeWS' licensing was proprietary and X won out.