All of what you say is logical except for a minor detail. The only reason all of those creative films in the 1970s were being made was because Hollywood was chasing money. Everyone was trying to make the next Godfather not because it was a great film but because it became the highest grossing movie in history, passing Gone With The wIND. iF the Godfather had bombed - which many studio heads thought it would given how much Coppola was spending on it- much of 1970s wOULDn't have hadppened. Indeed it is only because the lion's share of the movies you mentioned at the start of the article made lots of money for Hollywood that the filmmakers were allowed the freedom to make more.
Hollywood didn't give all of these creative geniuses the ability to make these classics because they were interested in art. The studio system had collapsed and something needed to take its place. Had movies like Doctor Doolittle and Hello dOLLY been huge box office hits we would have been getting studio musicals for the next decade. Hollywood only follows money, art is a secondary consideration. Had Star Wars bombed and Sorcerer been a smash hit we'd still be getting these films. Hollywood has always followed the money and always will. Art is an incidental byproduct and a second ary consideration.
I'm doing this not to be a pedant but because I basically have been doing this to everybody, even critics I greatly admire like yourself. Hollywood is a business first, it's not there to make art: that's at best a secondary consideration. I think you know that given your writing about blockbusters in this article but it's a lesson that I really need to push among my fellow critics. Perhaps it is nagging but critics don't seem to have learned this lesson over the century plus of Hollywood's existence. We have to keep pushing it.