For Display Port cables, if they're not certified, you run the risk of strange hardware faults at best, smoking hardware at presumably worst.

USB4 is tremendously more dangerous if the cable does something really wrong.

The problem is that you don't know if the logo is valid. Anyone can just print it on their product. Even buying from Amazon won't save you all the time.

To me it'd have been immensely helpful. If there had been 2 manufacturers with a logo (or a clear spec), I'd certainly have bought from them.