Capabilities are printed on the side of ethernet cables and the text printed on the cable rarely seems related to the actual capabilities of the ethernet plug. Some cat5e cables are rated for 1000mbps but will happily run 5000mbps or 2500mbps (because those standards came after the text on the cable was last updated), other "cat6" cables are scams and struggle achieving gigabit speeds without packet loss.
Plus, it doesn't really matter if you put "e-marker 100W USB3 2x2 20gbps" on a cable when half those features depend on compatibility from both sides of the plug (notably, supposedly high-end devices not supporting 2x2 mode or DP Alt mode or charging/drawing more than 60W of power).
USB cables push the boundaries of signal integrity hard enough that unless it's a 1 foot passive cable you're not really going to get any surprise speed boosts.
And when they upped the max voltage they didn't do it for preexisting cables, no matter what the design was.
> those features depend on compatibility from both sides of the plug
That's easy to understand. Cable supports (or doesn't support) device, it can't give new abilities to the device. It doesn't make labeling less valuable.