@andy2,
Again, I believe you are missing a third alternative:
I (or "we") don't know who is right.
Say we want to know if it's raining outside, and we can not tell from the windowless room in which we sit. One method is to get up, open the front door of the house and check if it's raining. Another method is to flip a coin and say "if it lands 'heads' we know it's raining."
If you use the coin method and flip heads it may in fact be TRUE that it's raining outside.
But that doesn't get around the problem that method used isn't one that, on examination, actually deserves our confidence.
It's the same when we are talking about audible differences that are either very small, or exist in areas that are controversial. It may BE that the manufacturers who claim their cables need burn in are right, and that it's a real, physical, AUDIBLE phenomena. But, if like flipping a coin, they are simply using the same anecdotal methods as any other audiophile....and more to the point....essentially the same subjective, anecdotal method as used by any other pseudo-science or fringe belief system (e.g. alternative medicine, psychics, etc) THEN it makes sense to point out these conclusions are not being supported by a reliable method.
Surely you accept that an unreliable method, or 'explanations' that haven't been vetted in a careful manner, used by many people, can lead to many people being wrong?
200 million people use homeopathy on a regular basis. Can they all be wrong? Of course. Same goes for any number of beliefs born of little objective, repeatable data and supported by subjective impressions.
It's why vast numbers of contradictory beliefs about the world arise in the first place. And it's why science arose as a method to help us separate the wheat from the chaff.
BTW, not all cable manufacturers seem to make claims that cables change with burn in.
And those include some of the most experienced and respected manufacturers. You don't see for instance Belden or Canare cable claiming cables need "burn in." And yet they cater to a massive, critical, often professional customer base. For professional industries, a cable - or for that matter capacitor etc - has to perform as one expects from the physical specifications.
It seems telling that the claims regarding long burn in times - "the cable is only going to sound better over time! Keep it in your system!" - come from high end cable makers who are selling at boutique prices....to audiophiles who are relying on subjective impressions.