IMHO, there was never a set of hard rules that enforced the split to any particular value. Business philosophy changed from a paternalistic profits + play a part-of-society view to the very literal greed-is-good view by the 1980s.

There was also a generational shift from business leaders who had been alive to feel the effects of the depression as well as when the rich weren't so insulated from the poor, to those where born well after those effects firsthand.