Since Wayland compositors handle input devices on a lower level than X11 window managers, every compositor has to figure out on their own what a “mouse wheel click” is:
(I think “Wayland compositor” is a misnomer. They are full-blown display servers that also do compositing, plus Wayland window management, plus X11 window management.)
One can only hope that all this eventually gets moved into the wlroots library. (I’m not sure if that’s possible, nor if people would want that.)