A lot of quack tech is technically somewhat useful. Oxygen-free copper, occasionally used in "audiophile" cables - technically is a better electrical conductor (compared to regular copper), by a whooping low single-digit %.
Exact same effect could be achieved by making conductor that very same single-digit % thicker. Which is an order of magnitude cheaper. And ohmic resistance is not that important for audio-cables anyway.
Sure, but we were talking about high-speed digital cables, not audio cables. When you're pushing 48gbps over copper (as in HDMI 2.1) the cable construction and connection integrity absolutely does matter, older HDMI cables don't work reliably at those speeds (if at all) despite having exactly the same pinout as the newer ones.
Gold-plating of contact surface of electric connectors is indeed genuinely useful, on account of preventing contact oxidation.
Assuming good contact in connector(s) is achieved, gold-plating does not further help with high-speed signals. What matters here - is wire/cable itself, specifically, tight control over where conductors are relative to each other and insulation, so that impedance is well matched throughout, cross-talk is minimized, etc, etc...
True audiophiles hold out for Low-background steel enclosures.