What's the deal with HDMI 2.1 cables?

[Ceme]

Following my recent purchase of an LG CX5, I ordered a cheap 'basics' HDMI 2.0 cable from a well known online retailer. I wasn't really expecting it to work yet it is working perfectly for 4k @120hz. The source is my gaming PC with an RTX3070 card and I'm playing games and streaming movies with no problems at all.

So why are we being conned into paying out 5x more for a certified cable. Am I missing something?

 

[Ceme]

Ok. The length of this one was 1.8m, I didn't realise it was more sensitive with 5m +. It just reminds me of the old days when HDMI had just come out and retailers were trying to convince us we needed to spend silly money on cables.