There is rather a lot more than USB going on in there.
USB, FireWire (not spoken by many of the later models; but I believe still a valid charge source until the end), some analog audio and video, power supply for peripherals, some serial for keyboards and other low-speed accessories, etc.
The move to the lower pin count cable required killing a lot of directly accessible I/O, with accessories adding those features to compensate.
Perhaps the most dramatic example are the new video-out cables. Since the connector doesn’t have pins or bandwidth for HDMI the cable has a SoC in it that boots a teeny little kernel when plugged in, listens for a compressed video stream over USB and handles HDMI output. That’s why the hardwired video out has similar compression artifacts to an airplay stream; and why some of the older, weaker, devices only supported video out at lower resolutions than they supported internally; because they couldn’t compress the higher ones in real time.
