What gets me is how old Wayland is. It's now older than Linux itself was when Wayland started. It started in the era of 2.6 kernel series, when most software was still 32-bit, systemd didn't exist, when Motora Razr was more common than iPhones, when native desktop applications were still the norm, Node.js didn't yet exist and Google Chrome was a completely new beta browser. Wayland is now reaching feature parity and some kind of "it works out of the box, usually" state when it's from a completely different era of computing.
The nearest point of comparison is perhaps systemd, another Linux project that is very large in scope, complicated, critical and must interface well with lots of pre-existing software. Four years after Poeterring's "Rethinking PID 1" post that introduced systemd, it was enabled and in use on many distros. The conservative Debian adopted it within five years. Now it's been clearly a major success, but Wayland has been perhaps the slowest serious software product to be in development.