Hockey: Yes it is just 1 and 0 logic, however if the signal quality is poor because of a poor quality cable, the D/A decoder chip in your DAC will have to work harder to find the correct signal and decode it. This will affect the sound. The poor cable can also affect things like the timing and pace of the signal (and hence the music), even though all the data will arrive. These things are not an issue sending computer data, unless you get upset that your computer data arrives a fraction of a second later than you expect.
It is the same as high speed data (faster than DSL) needs a better quality cable than standard telephone cable. I live in a rural area and have never gotten a faster connection than 43.8kps on my 56k modem. I usually average around 38.6K. The quality of the phone lines is just too old here. I can get digital cable TV here. However, they had to install better quality cable in the ground to get it to work. The old cable TV lines could not handle the digital TV signal well enough to actually see the improvement.
I am actually on your side in part. While I believe a good digital cable matters, I doubt is it as crucial as an analog audio signal.