Let's take a look at those articles shall we?
Article has zero testing, and zero evidence. It merely gives a potential alternative, which neither proves Burn-In isn't a thing, nor does it match your original claim "it is your ears adjusting to the sound". The fact that you linked an article that makes a different supporting argument than the one you made shows you're more concerned about winning the argument than actually being correct.
Even in this article it sasys "Matt Engstrom, director of monitoring products at Shure, admits there is evidence that suggests transducers in larger headphones can experience burn-in, and that this could, in theory, produce different sound over time". This article is mostly about "earphones" or "earbuds", and how they believe that the BA drivers in earbuds are too small to experience this.
This clearly shows that instead of doing actual research or testing you just googled "why my opinion is right" and it's this kind of confirmation bias that completely kills any bit of credibility you may have been able to muster.
Again, right from their sourced expert in the article, "It's clear to me, having had the experience, that there is indeed an audible difference when breaking-in a pair of Q701 headphones. I've seen measured differences, and now experienced audible differences. While the measured differences are small, I believe the human perceptual system is exquisite and able to perceive, sometimes consciously and sometimes sub-consciously, subtle differences."
It also goes on to say that the company Shure has been testing headphones for years and has found that the drivers do not change over time, but does not provide any sources. In fact, it is directly contradicted by the previous article you linked where the Director of Monitoring Products at Shure claims there IS evidence to suggest that they change over time.
The articles you linked were questionable at best, none of them did any actual testing, and none of them actually supported the original claim.
You also have to remember that it was YOU who presented the claim that "burn-in isn't real, it is just your ears adjusting to the sound" as fact, therefore the onus is on you to prove your statement true, not us to prove that burn-in is real (since I never claimed I knew whether it existed or not, merely that I haven't seen any compelling evidence to suggest one way or the other).