Perkadin,
I agree with you that listeners tend to be biased to favor the “improvement” they invested in and may go overboard in a particular direction. You rarely hear someone say that a particular tweak made the sound worse when any such change should have a fair chance at being for worse.
When it comes to vibration damping, I’ve experienced where some additional damping was an improvement, but more than that sounds bad; it is NOT the case that more of something good is always better. I heard a demonstration by a representative from Symposium who put a vibration damping shelf under a CD player and it improved the sound (everyone in attendance agreed). The next level up in their product line slightly improved the sound. But, the flagship shelf made the sound too dry and unpleasant; even the Symposium guy agreed the sound got worse. How could better damping worsen the sound? I don’t know, but I heard it.