Well, you do need to be specific because like 99% of headphones terminate in a 3.5mm jack or a quarter inch jack. You were referring to a vert very limited subset of headphones.

It’s honestly kinda dumb to buy a headphone, which only needs an analogue voltage signal to work, that terminates in usb-c. Specially considering that there are still loads of devices that don’t have that port. Even if a computer has it, it’s likely that it only has 1 or 2 of them which might already be in use. For example, my work laptop has 2 usb-c and I’m using one of them to charge it and the other to connect a monitor.