I blame it on the Bose 901. Prior to the introduction of that power-hungry loudspeaker, a 50 or 60 watt (per channel) amplifier was considered all a speaker, even the inefficient acoustic suspension designs of the day such as the Acoustic Research 3a, needed. Plus, that’s about as powerful an amp as was available at the time, one exception being the McIntosh MC2100 (105w/ch), which I owned. That all changed with the appearance of the Phase Linear 700 (350w/ch). The power race was on, along with as-low-as-possible-no-matter-the-sonic-penalty low test-bench distortion figures.
J. Gordon Holt with his Stereophile Magazine alone, until Harry Pearson published the first issue of The Absolute Sound in 1973, fought against the insanity that followed. Luckily, at about the same time, the emergence of high end amplifiers, designed for sound quality into speakers rather than ultra-low distortion specs into test-bench simulated speaker loads, were beginning to appear in the new audiophile dealer network springing up around the country, selling the pioneering Audio Research Corporation products (with their tube amps, tubes having been abandoned by the hi-fi industry years before) and other perfectionist sound quality designs.
It’s important to remember that a doubling of output power, all else being equal, increases SPL by only 3dB. A 300w amp, identical in every way to a 150w one save power output, provides only a 3dB increase in sound. Big deal.