Wayland is a display protocol, and the base of that protocol is deliberately really minimalistic - it’s there so different programs understanding the protocol can draw their rectangular windows on to the screen and that’s it.
But Wayland developers did think of additional requirements but were thinking that ad hoc inventing something that may or may not be implemented downstream would be a bad idea (it is), so they created a standard way of adding extensions to the base protocol - which are created with cooperation between major desktop environments - the actual implementers of said protocols.
And as of now, wayland is pretty feature-compatible with x, in an actually extendable way (much more close to the UNIX philosophy if that’s your thing).
But Wayland developers did think of additional requirements but were thinking that ad hoc inventing something that may or may not be implemented downstream would be a bad idea (it is), so they created a standard way of adding extensions to the base protocol - which are created with cooperation between major desktop environments - the actual implementers of said protocols.
And as of now, wayland is pretty feature-compatible with x, in an actually extendable way (much more close to the UNIX philosophy if that’s your thing).