Apple actually used to do this on MacBooks - one of the USB ports has mux circuitry that can be switched to an SMC programming mode that merely uses USB as the

Apple actually used to do this on MacBooks - one of the USB ports has mux circuitry that can be switched to an SMC programming mode that merely uses USB as the physical connection for their SMC programmer tool, bypassing the USB host controller and not using the USB protocol. It was removed in the 2016 onwards MacBooks as the T1/T2 supersedes the SMC, so it follows the same design patterns as iPhone hardware.