The wattage wars go back to the Mid late 50's with FISHER, Scott, Sherwood, McIntosh, etc., all trying to best each other. Before then most consumer amps, consoles, etc., ran 6L6 or 6V6 tubes, with the occasional EL-84 or EL 34 thrown in for good measure. In 59-60 the 7591, and other higher powered tubes came out. In 63-64 Transistors came out and the wattage wars became more visible, and you now had Japanese Co's, vying for space. PIONEER came out with the SX-1010 in 1974 and everyone was scrambling to catch up, IIRC Marantz was the 1st to catch up with a 100w receiver. Then all hell broke loose and everyone was engineering higher powered receivers and amps. It was highly visible as Vietnam vets would buy these Japanese units and bring or send them home. The guys in the states didn't have access at 1st, After a while the gear started coming in and the games began.
Later classic stereo history is what I'm mostly familiar with in learning and enjoying because of my beginning interests happening with whole 100 watt plus era. (Would have more of a growing interest in earlier but not much "easily out there" in comparison, and too busy with what I have now!) Thanks for adding your perspective.