Usb type c is a connector type. Not a protocol, you are able to run different protocol through the same physical line as long as both side understands it. PD, HDMI, miniDP, PCIE, earphone, and probably other device run through the exact same line with different protocol. And vendor is also allowed to add their own one. Apple also don't need to accept all protocols above except charging. What is the point to introduce new connector type every single time you want to add new compatibility? To earn more money from selling gadget?