Originally Posted by FOH
At bare minimum, at least the dealer could offer help with setup, placement, and most importantly room acoustics, if the unsatisfied Mr Deep Pockets bought said items (upgraded power cords, speaker wire, DAC, high-quality power outlet, etc)
From a dealer's viewpoint, its all about costs and benefits. All of the devices you've just mentioned have trivial installation procedures and skills for best results, given that best results are trivial changes to sound quality. From a dealer standpoint they are ideal, because it is very hard to ruin or even change a system's sound with snake oil nostrums.
All one has to do is follow the threads about acoustics and measurement software here at AVS to realize that their installation and usage involves non-trivial procedures and skills and involve a risk of actually changing system sound quality. We also know that anything that actually changes the sound quality of an audio system has considerable risk of buyer's remorse.
We now know that there is at least a 30-40% chance that a placebo will create the perception of a benefit in the "patient" as determined by a skilled professional. In the case of home hi fi, the determination is made by a person no special skills and with a considerable investment in a positive outcome. We already know that the perception of benefit becomes then very high - probably 80% or more.
Its all about costs and benefits as seen from the dealer perspective.