I believe the idea was that a "true" AF-S lens allows a manual tweaking of the focus while in AF mode in the event that the user thinks AF isn't doing what they want. However, all AF-S lenses are/were not "true"AF-S in that sense, and did not allow manual override of focus while in AF mode. IIRC, it's the less expensive AF-S lenses that don't allow it.
Please tell me why Nikon did not throw in a VR off function with the latest 70-300 AF-P lens FW update. :o(