Yes, I think some of the small differences are overstated, but that is with reference to how my hearing was a couple of years ago. Sadly my hearing now isn’t up to discerning even very obvious differences, and that is my point, we are often talking not so much about equipment differences so much as our hearing ability. Now I could, but wouldn’t be so arrogant, dismiss things just because I couldn’t hear them now! I could, but wouldn’t be so super arrogant, accuse people of selling foo (as has happened to posters in this thread) just because I can’t discern what it does now. That doesn’t mean that their aren’t charlatans in the industry selling outrageous foo but if we personally don’t have the hearing to assess things then we are down to the measurement brigade and are at the mercy of their methodology, not to mention ideology. Sometimes one just has to accept that one doesn’t know, one way or the other.
Typically hearing loss due to age is, as you say, a ski slope in the upper frequencies, perhaps iirc with a notch at around 1.5 kHz due to exposure to damaging loud sound, well within the region that affects our listening to music, particularly if you consider harmonics. Hearing loss might not affect each ear equally and that is before you get into the esoteric world of reverse slope hearing loss. It is of course much more complex than just frequency response; I mentioned ossicular fixation as just one possible problem. If those tiny bones in the middle ear aren’t transmitting vibrations to the inner ear properly then it will likely affect our ability to discern the effects of noise under discussion.
All I’m saying is that just because we, individually, can’t hear something it doesn’t necessarily mean that others can’t.