I do understand and appreciate your statement. But you have to realize that as much as we all want to think our sensorial skills are without imperfection, that is simply not the truth. So, I believe you when you say you could hear no difference, but that does not mean differences cannot be heard by anyone.
You also cannot reasonably discuss audible differences in cables without defining both the equipment and environment. I think many would agree that if a cable does make a difference, the change is more on the subtle end of the spectrum, but there are exceptions to everything. And if a cable is to have a fighting change to make an audible improvement, the system must be at a level to allow for such change to be perceptible. The same goes for room treatments - one of the most overlooked aspects of high-end audio. If the room is creating an “audio spaghetti” due to reflections, comb filtering etc., even if the cable was making a difference, it will not likely be perceivable.
I have no idea about your listening skillset (could very well exceed mine) or the system in which these cable comparisons were made (could very well be superior to mine), but I do know that such a definitive statement ignores countless variables that are at odds with that claim.
Above all, I am not trying to be disrespectful or argumentative so please don’t take this as an attempt to start a brawl. It is just a difference of opinion.