think that the sound quality that a person with an ordinary income can buy today is miles ahead of what that person could buy 25 years ago and is getting better all the time.
I agree.
JGH beef seems to be with a large portion of the high end which has gone euphonic and nice sounding in preference to accuracy (according to JGH). You may have put your finger on the issue...digital and CD and cheap transistors brought excellent sound cheaply to the masses. This squeezed a portion of the high end towards a struggle for differentiation given much higher prices which may have led to the euphonic nice retro high end approach that contrasts with much of the regular low cost fare. Kind of like how Rolex survives today against cheap digital/quarttz watches.
Of course there are many exceptions even in the high end. For example, Evolution Acoustics MM3 looks like a serious attempt towards further accuracy...