It's true that some people can't make certain distinctions that other people can make with ease. As an analogy, a few people can throw a 97 mph fastball; I sure can't. My inability to do so, in itself, doesn't mean that no one else has the ability. To show that something is possible, it's not necessary that everyone be able to do it; it's enough that someone can.
The thing is, though, that if such a someone really does have a particular ability, he/she is invariably able actually to demonstrate or prove it, not just to assert it. I might have been disinclined to believe that anybody could throw a ball 97 miles per hour, but when you take somebody like Joba Chamberlain out to the ballpark, rig up the radar gun, and find out that, yes, he can throw that hard, then he's proven that he can do it. If he can't prove it, he can't do it.
What bugs me about many self-proclaimed audiophiles is how resistant they are to the idea of any kind of proof other than their own assertions. Surely, if they had such refined powers of auditory discrimination, it would be the easiest thing in the world to prove it--just as it's easy to take a pitcher out to the ballpark and find out if he can really throw 97 mph. Just rig up two sets of cables, say, in a blind test environment, and see if you can bat significantly better than .500 in telling them apart. If your hearing is that good, you could do this easily. Yet that hardly ever seems to happen in "high-end" audio.