Interesting thread, and a lot of good points posted. I think regarding the cable, I'm not so sure how cable can significantly affect sound, however it can certainly affect the 'feel' and consequently the quality of the listening experience by the user. I used to believe cable can change sound in a way that is clearly perceptible. But the more I spend time altering between one (copper/silver, cheap/expensive, or what have you) model to another, the less convinced I am to any change I was hearing to be attributed to the cable. It is so slight, and in science it can be alikened to be within the margin of error (insertion depth, skin condition, expectation bias, mood, etc.) . And so I concluded that at least to my ears cables don't significantly affect sonic qualities, however it may affect our subjective perception/impression of the sound due to many other unaccounted factors.
But our listening experience is by definition subjective, and therefore can be irrational sometimes. The number of times you've listen to a song even plays a role in influencing our enjoyment. The first time you listen to a song, and the 100th would certainly feel different, and be perceived as such to our brain as well. And it's interesting to observe the neurological connection here, because this is in my opinion where the proverbial rubber hits the road, or at least as far as we know (who knows, there may be other elements in play to our perception, human experience is a very weird thing).
I think that if someone can hear the difference between cables, and perceived that difference as being significant in increasing/reducing the quality of their listening experience, then that's OK. I think it would even add some more richness and fun to this hobby. Let there be more option, freedom and colors to choose from, and let the market flourish with innovation, and products of human creativity/ingenuity. I think there are many 'best', and they differ to each individual, their preferences and qualia. My point is, not everyone hears the same. And in the face of something more complex such as our perception, it's not always easy to point what causes what.