Many expensive headphones are overpriced, but there is a very obvious difference in sound quality between very cheap headphones and medium priced ones. Either they're measuring the wrong thing or their headphone sample isn't what I'd expect.
"New study shows no difference in speed of blue vs. red light!" We always ascribe waaay to much importance to what we can measure easily.
I don't think they're measuring the wrong thing, although a human might be interested in more things than frequency response.
Just goes to show that perhaps the most important thing in selecting headphones is comfort and the context in which they will be used.
For "audiophile listening experiences" an equalizer and CA-style cans might be a good idea and give a lot more bang for the buck than shelling out several hundred just for the cans.
"However, the variance in low-frequency response seems to decrease with increasing price, indicating an improved bass response measurement consistency across headphones in the higher price range."