HDMI has several versions with compatible connectors. Later versions of the spec use some previously-unused pins, if you buy a cable without those wires connected (pre-1.4) you won't get Ethernet over HDMI or the audio return channel. Also, just like Cat 3 phone cable, Cat 5/5e/6 optionally-shielded Ethernet cables, the data lines can be designed for different clock rates.
An ancient cable wired into the walls of your early-2000s home theater may legitimately not support your new 4k HDR gear.
And frankly - the know-it-all customers are still right...
In the large majority of use-cases, the cheap cable is going to do fine.
In the small minority of cases it won't... choosing to buy the newer spec cable from a company that's promoting obvious bullshit (like gold contacts) just screams "I'm getting scammed". If the only version of the new spec HDMI cable you carry is a needlessly upmarket and expensive version of the cable... assume they're slinking off to amazon for good reason... to go buy the cheap version of the right spec cable online.
An ancient cable wired into the walls of your early-2000s home theater may legitimately not support your new 4k HDR gear.