A big security advantage of Wayland is not allowing applications to read input devices all the time. Having `/dev/input/*` accessible to the user account subverts this advantage.
libudev-devd was opening the evdev devices to detect their types (mouse, keyboard, touchpad, etc). This does not work when `/dev/input/*` is inaccessible.
With the kernel exposing this information as sysctls, we can work without `/dev/input/*` access, preserving the Wayland security model.
The devctl notification is not important for this, but it makes more devd rules possible.