The explanation I was given back in 1983 was that when a meeting gets to be a certain size, it takes too much time and is distracting for people to clap or call out "yes" or "I agree" etc. The Bay Area anti-nuke hippies I was hanging around had already adopted twinkles and other hand gestures at their meetings, which means that a process of experimentation and refinement had been taking place for at least a few years prior. When I was on the East Coast among anti-nuke folks in 1979 and 1980, there were some hand gestures for standardized non-verbal messages but it was different -- except for the twinkles.
Would *accuracy* be a more interesting term than truth? Would that fit in better with your pomo bullshit?