this is counting the xfree86 legacy. That one was started in 1991 and 17-18 years old when wayland was startet in 2008 which is now 18 years ago. Counting the time before xfree86 doesn't make much sense. While initial implementations of X where older than that, those early implementations don't really have much in common with todays Xorg. And the problem is, that wayland is still much less mature than Xorg was when wayland was started.