Steam can map scrollwheel, amongst other things steam can map for controller to access tap strafe. My mouse provider let me remap everything on my mouse for instance mousewheel to be w. Apex legends cant see the difference it reads the hid. Also making a small thing to give hid input from scrollwheel wouldnt take more then a few minutes for a coder for the people who dont have the options to remap outside Apex.
And the state engine dont have a spesific block to discern strafe or tap strafe, the entire move is a side-effect so its outside of code control.
If you for instance define strafe as hitting a and d, ok then you cant strafe while shifting from your flatty to mastif (shifting weapon means you stop and stand still, youre dead) and that is for people not using tap strafes. Its been done actual tests with actual people on an actual server to try different ways of stopping the tapstrafe and its proven extremely hard.
Sidenote: many people shift weapons on 1,2,3, ok try check how many percentage that is, ill promise you most use scrollwheel today as it has become some sort of defacto standard in misc shooters. Btw do you know why some people spend thousands and thousands of hours in some games, I am soon over the noob mark in Apex - just passed 1800 hours and soon claiming the 2K mark, its one reason and one reason only, I can still progress, there is always something new to master. If that complexity is removed from the game i do think it loose its edge against other titles, today there is several ways of becoming insane in this game, insane aim, insane movement, insane placement or a combination of the 3 - this is what makes apex ahead of the curve on the rest of the titles in the category, loosing one of them and they compete at the same level as the rest, this is why Respawn is very very careful around this, they are fully aware of why they are no1.