Probably because there was an oversupply of unskilled labor starting in the 1970s, especially as Japan and Germany started heavily exporting and Europe in general recovered from WW2. Another factor was markets became much bigger as a result mass communications that allowed supply chains, manufacturing, sales to grow even bigger and gave more power to executive groups of corporations. One small but high profile market that underwent big changes was pro sports. Salaries of top baseball and football stars exploded in the 70s and 80s. Some corporate ceo's (Lee Ioccoa), pointed to this and said it showed that star players were worth big salaries because they were the money makers for the team and the same applied to corporations because the ceo was the 'star' player.