The rotating pair can send independant signals.
Thats why USB-C have more or less the same speeds than HDMI, while the HDMI have 22 connectors.
Compare what is comparable, you can't use your USB-A to display 4K-60Hz video, but you can with your USB-C, or HDMI.
Also: USB-B micro connectors might have 5 pins, but the cable itself has 4 wires. The OTG pin is grounded in the connector. This is actually why I said "4(ish)" in my original post.