It's the cable that is supposed to reverse itself and not the device? I'm not entirely sure I buy that - seems like it would add a lot of unnecessary complexity to every cable.

The terminating device(s) are the ones that do the flipping, not the cable. You can take a cable that works either way between two high-end device, and then connect it to at least one low-end device and it will fail to connect for one of the two orientations.