Why do digital coax cables matter?

My brain tells me no two cables that are physically different conduct electricity (or light for optical) the exact same way. So there has to be differences to some degree. The question for me is then how much and are the differences significant enough to matter in practice?

I wonder about digital ICs in general in this regard more so than analog ones. No two analog ICs usually sound the same to me. But on the several occasions where I have compared different digital cables going into my DAC(s), if there was a difference, it was not enough for me to take clear notice or even care. I know that in theory different levels of jitter is the result and that jitter level matters. But does it really in practice? It's something I have not been able to discern with my own ears so far.

So I wonder.....

Seasoned got it right, but I still wonder with current state of digital technology if in practice it is really that much of a problem with most modern gear. Digital technology in this regard has come a long way since the CDs outset around 30 years ago. That makes a big difference.

Of course to whatever extent it may still be a problem in practice, audiophiles will care more about it than most normal people.

In my case, to date, I would have to say that digital cable tweaks have made the least difference of most any tweak I have tried. Most others (digital and analog related) I hear a difference. With digital cables, I am still waiting. I have mostly compared optical versus coax to-date specifically. These are each significantly different so I expected to hear something but have not so far. I have also yet to hear a practical difference through the same DAC from various digital sources. I have compared several digital sources including Marantz DVD player, Denon CD player, ROku SOundbridge and Logitech Squeezebox. They all tend to sound similar and essentially equally good to the point where I determined it did not matter to me.

"Perhaps you didn't test the right cables, or your preamp creates enough distortion, noise and compression that you dont hear the benefits because they are masked. This is fairly common when using an active preamp. I dont use a preamp, so I dont experience this masking anymore. It's a system after all, so every component and cable matters."

Maybe. But I do hear differences in most everything else I tweak beside digital source and ICs. So I think I have the relative magnitude right at a minimum. I hear a lot of systems and live music and I do not hear any distortion or dynamics issues of significance, but of course we know such things are always in play to some extent in home audio.