When I first started blogging in 2009, I was asked if HDMI could accept input and output over the same connector (not precisely at the same time). Of course, a graphics card with an HDMI port on it is most likely only for video output and not video input. Of course, the answer, therefore, was no.
But why not?
Well, the answer is that it's just not been implemented. That's because HDMI was never designed this way. Usually, when a connector (such as USB-C) is bidirectional, a handshake protocol is implemented that decides the connector's data flow.
Some features of HDMI, like Audio Return Channel (ARC) and Consumer Electronics Control (CEC), are, of course, bidirectional; for CEC, for example, the device can control a TV, and the TV can also control the device, and for ARC, the audio can be sent back to the device.
