I never understood why this was always seen as such a constraint. It’s three (or four) pins! It doesn’t even have to have the “hole” form factor. You could have them all in a straight line and then place a headphone jack AGAINST them. I always thought a magnetic TRRS set of pins along the side of a phone could work. Add a sleeve to the connector’s side too. Heck you could standardize a flattened TRRS or whatever that would still slip readily into a typical jack.