Great post!
I will only add that the psycho-acoustics dimension add to the physical engineering dimension and made it an inescapable dimension of audio ..
like the trade-off principle in engineering ..
Then those claiming that this principle dont apply to a "high class" of audiophiles whose status is over this principle with no budget limit spoke non sense ...
I create the concept of "minimal acoustical satisfaction threshold" to descrive the state of satisfaction of low cost system/room and "maximal acoustical satisfaction threshold" to describe the state of satisfaction of high cost system/room...
In these two cases according to "the principle of diminishing return" there exist an "optimal acoustical satisfaction threshold" ...
Snobism has nothing to do with acoustics or design engineering and their trade-off relation in Room constraint...
The "law" is just an equation, y = 1/x. It doesn’t just apply in some cases or to some people, it applies in all cases. Though subjectivity & opinion can bend your world any way you want, this doesn’t change reality. "Diminishing returns" (1/x) applies in a wide variety of applications and natural systems.
In the plot of -1*(1/x) below (-1 is just to flip the plot horizontally as people, in this case, are trying to maximize y), the x axis would be cash, the y axis would be "perfect sound quality".

