Irrelevant? Not really. For every cabling standard, someone comes up with a way to use pre-existing cables so it's not necessary to retrofit new, in building where it would be difficult, if not economically unfeasible. That's why HDMI can now be sent via Cat5/6/7 over 500' and more. It can also be sent over RG-6/6Q. Then, each end needs to be terminated in a way that the source and display can handle the signal. He was probably bringing up the Cat6 and 7 because far less consumers know about them and when someone talks about several cable types at one time, some people are intimidated. I have a customer who gets nervous just looking at the wiring behind his cabinet and his system is very simple. Most people who don't deal with this stuff see a whole bundle of wires and those who do work with it see several cables of various types, which all go someplace specific.
