I don't know why the laws of human hearing are'nt appreciated more and respected.
A lot of what we know about human hearing rules has only been worked out in the last 35- 40 years. But by 50 years ago, most of the understanding of how to analyze audio products was already in place. To get the really low THD specs you have to use feedback; when it was discovered that the human ear uses odd orders to detect volume (and also that trace amounts of odd ordered harmonic distortion is really irritating to the human ear), the fact that negative feedback was contributing to that became an 'inconvenient truth'; essentially the audio industry paid no attention and may have even swept the discovery under the carpet.
So for the last 45 years or so the spec sheet has told us nothing about how an amp sounds- in fact as you say may even show an inverse relationship to the sound of the product. But changing the way the audio industry does things is hard- there are a lot of companies that simply will not accept human hearing rules as important, even though they pay lip service.
The result is that audiophiles, no matter what they have read or heard from others (and no matter who those others are) have to audition things for themselves. You would think that the spec sheet would help in that purpose- what else could it be for??
Of course the issue is pursuit of the almighty dollar. Tube amplifier power is more expensive than transistor power and high efficiency speakers are more expensive than low efficiency speakers. But the hype is that the cheaper transistors and lower efficiency speakers are somehow better because of the 'specs'! Whatta world!
