Why isn't libeis implemented as emulated devices?

I don't have in depth understanding of emulated input however I am curious of the following:

My current understanding is that libeis is a standard/protocol implemented by a Wayland compositor to accept emulated user input to forward to windows.

Why was that approach taken instead of libeis registering a /dev/input device(s) and simply forwarding the requests of libei clients. This approach would bypass the need for the compositor to need to implement a protocol. It also has the added benefit that it will work with any compositor.

The only downside that I can think of is that that would probably require elevated permissions for the emulated input device creation.