Following is not my observation. I read it somewhere (I wish I had remembered). I think this is a very important observation about the pivot role of cinema in modern societies.
After 2 wars with Pakistan India was passing through a very rough state of affairs in the early and mid-1970s. Poverty was at a peak, the population was exploding, people were literally living on streets, alcoholism and prostitution were at rampage, basic necessities of life were counted as luxury and corruption was a way of life. For poor men cinema was the only cheap entertainment but it was all glossy with romance. Amitabh came on screen as a rebellious young angry man who defies all norms of society and fights against injustice. His movies Zanjeer, Sholay, Deewar, Don etc were prime examples. Indian society instantly identified its hidden frustration on the cinema screen. They found Amitabh as a reflection of their fantasies. His long stature, deep voice and expressive angry face were in perfect coordination with inner desires of people.

ke dadi sahi kehti thiN.