Interesting, Swerd. I can certainly see how, in an age where "consumer electronics" encompasses a breadth of products clearly unanticipated in the world as seen in 1970 or so, audio power specifications might be seen as a "back burner" issue, regardless of how important it might be seen by our small subset (those who take a serious interest in audio) which is in itself of a subset of a huge industry (consumer electronics).
I did, at one time, delve fairly deeply into the proposed revisions of the 1974 FTC Power Rule, and once I concluded it was likely dead in the water, I put it behind me. My previous comments were from memory based on what I found at that time.
The original rule had broad support from serious audio manufacturers, with a significant portion of the industry wholly based in the USA. Neither can be said to be true today.