Re: Let this be a warning to all decent people
Quickly adapting circumstances favors the social and intellectual elite. More intelligent people are more adaptable. The average IQ is higher among programmers than manual laborers; you have to learn more new things faster (that new javascript framework won't research itself) to do well in the first job than the second. As society gets more technically complex and more jobs are automated or become higher-complexity, this ostracizes the less-intelligent.
There's something similar for social mores, taboos and morals. They have their own shifting fashions, and those higher in 'social intelligence' and spare time- slack- can adapt faster, keep up with the newest buzzwords and faux pas. This all serves as a form of social barrier between the elite classes and the proles.
Perhaps, when free resources dwindle and competition rises, people become more cutthroat about maintaining strict social divisions like this, and so the rate of taboo evolution increases?