I have no problem admitting I have less knowledge about this subject and far less credibility than any other poster in this thread. For some reason, I'm going to pretend the opinion of a total home audio/home theater novice will be a worthwhile contribution, so bear with me.
I've read enough here-and thought about what seems logical-to not question the fallacy of exotic cabling being a game changer/normally functioning amps sounding the same/etc.. Intelligent individuals with a ton of expertise have convinced me.
That said, I do feel I have heard audio quality differences in the avr's I have had. I can admit this is most likely in my head and double blind testing would probably prove me wrong. But if I feel that my old Integra sounds different or better than the Sony I had, it kinda makes it true, even if only to me. So a little part of me feels we shouldn't tell these people they are wrong.
On the flip side, I believe spreading these notions can be shady and just plain wrong. I used to be a satellite technician and the company forced us to pimp higher priced Audioquest hdmi and optical cables. It was told to us there is actual video or audio improvement and most of us believed because we didn't know any better (I hadn't yet had much interest in home theater). After a while I started wondering...."it's digital. I'd think it either works or doesn't, there shouldn't be much difference". I started paying attention and concluded they didn't sound or look any different from the cheap cables we gave away for free. Unfortunately, most customers were as ignorant as we were and saw us as experts. If we said more expensive accessories were better, they assumed it to be true. I soon grew to feel dirty trying to tell people they should upgrade hdmi cables for their non 4k tv's or that an AQ optical cable would be a better choice than any cheap hdmi for their audio. I felt like a jerk and it was a main reason I moved on from the company.
If people like me want to throw out logic and believe this component really does "sound" better, those who know better shouldn't try to shame us about it or convince us we are wrong. However, it is also irresponsible of people who throw aside silly things like science and testing in favor of our subjective opinion to insist the experts are wrong and that those who don't know any better should invest money they may not have or could really use better elsewhere.
tl, dr: if people want to think magic cables or similar are better, let them think so. It does to them. If you do feel that way, don't trumpet your beliefs to people who may believe you without some credible evidence to back you up.
I still have several of those AQ cables. While no noticeable quality difference, I will concede the build quality has proven better than any of the cheaper cables I've since acquired.