Earlier quoted context omitted.
If a device has an HDMI port I know I can use that to connect a display. I don't know details like the supported resolutions, but at least I know that's a supported use case. If I notice that a device has a USB-C port all I really learned is that it has a USB-C port. Who knows what it does.
But that's most port standards that have ever existed. What can a device do with a parallel port? A serial port? A SCSI port? A Firewire port? Who knows? It's up to the device. It can certainly send signals over that port, of some kind. But what kind of signals? Up to the device. The host can hopefully probe a device-class out of the client and stand up an appropriate driver to talk to it. A CD player has a 3.5mm aud…
With USB-C, whether or not a device will do all, some, or any at all of its functions, depends not just on the device, but on what you're connecting it to and which one of the countless types of cables you happen to have, all of which look identical to someone who's not an EE with appropriate equipment.
Makes me think, maybe I should start selling USB-C cable testers, because if old USB taught me anything, is that you can't trust cable manufacturers to not lie, even if the cable standard is as simple as it gets.