Like the pencil these are for specific subsets of use cases, they are not a primary interaction mode but more like specialist support for optional peripherals,

Like the pencil these are for specific subsets of use cases, they are not a primary interaction mode but more like specialist support for optional peripherals, the same way desktops support graphics tablets and trackballs. When I described Mac interfaces as keyboard/mouse you didn't say "oh, and also graphics, tablets, trackballs and VR headsets". They're an edge case.