@DPI Wizard I figured out why people think the controller settings affect the mouse input at least.
The soldier zoom sens multiplier and ADS FOV etc are obviously global functions that are clearly not "gamepad" settings of course, but because for convenience these are exposed in the controller menu too, players are not realising that they are global functions and not controller stick settings.
This actually make total sense from a code perspective, no point writing two functions that do the same thing of just scaling camera speed by a linear multiplier, but the way it is presented in the UI has confused people into thinking they are gamepad settings.
So it seems DICE just need to update the UI, rather than the mouse input lol