Nikon included the capability to fine tune the AF system for the reasons described in the post #4 link above which should be very rare situations. Unless the camera and lens combo shows consistent back or front focusing there’s no reason to use that feature and needing that feature is much less likely but not impossible with mirrorless cameras.
IOW, it’s there because it could in some cases be useful but as folks have pointed out above those cases are pretty rare.
There are several camera fine tuning features like exposure fine tune and white balance fine tune that can be useful in very specific situations but Nikon would likely suggest that most folks shouldn’t use them as unless the photographer knows exactly why they need to make those adjustments it’s probably best to leave those fine tuning options alone. AF fine tuning is similar, unless there’s a clear and repeatable front or back focus problem it’s best to leave that alone and that’s even more true with mirrorless cameras.
