If all HDMI cables are basically the same design, pinout, etc. how have they been able to double, quadruple, etc. the bandwidth on them over time?

Question

Going from HDMI 1.4 to 2.1 there is a 5x increase is bandwidth. Is it because the cables themselves were never the issue but it was the connectors/chips in the devices themselves that couldn’t handle it?

I know part of it is the actual quality of the cables themselves and tighter tolerances, more twists in the wires, material purity, etc. but I can’t imagine that alone would be enough to fully account for this.

In: 565

Answer 1

Imagine a small stretch of road.
Only one car can travel on it at a time.

Now you have the technology and split the lanes so you have a car going both direction at the same time. Just one car per lane.

Now you have the tech and made it so you can multiple cars on the road at the same time per lane.

The road is always the same, you have just learnt to utilise it more efficiently.
Now apply the same concept to cables.