There's a bit more to it than that. An HDMI cable contains three serial data links, each operating at roughly 1.5Gbps. At rates that high, some shielding is required, or the cable will pick up enough noise to damage the signal. The HDMI link has some error correction (contrary to a comment on that site) whereby 8 data bits are transmitted using 10 bits on the wire, so minor errors are tolerated.
The important thing, and the central argument of that article, is that with a digital link, once there are no bit errors, no further improvements can be made, and even a cheap cable is plenty good enough for a short HDMI connection. Gold-plated connectors are still a good idea. Corrosion is as much of a problem there as anywhere.
Should you use a truly awful cable, and those do exist, you will probably notice an occasional "spark" on the display.