Thanks for the reference, I haven’t read much around Thalberg but as a ‘producer’ of influence he seems very much tied to the American/Hollywood system and economics - Thalberg would seem to be an exception rather than the rule.
In a way a producer is much like a CEO moving from production to production… their baseline is their commitment to the investors and shareholders first and capitalist trickle down economics will allow for creative stuff to happen. Thalberg had this balance right.
In way more many cases the producer packages the creatives together; writer/script, director and more importantly box office star power. And has the power to ‘replace’ any of these key roles!
Of course there are directors, like Lynch that have some sway as they are stars in their own right… but then there are other cinemas within the US and the rest of the world that doesn’t really work that way… can’t really imagine any producer having much sway over Carl Dryer, Antonioni or Ozu.
Within American cinema where was the producers influence over directors like John Waters, Andy Warhol, Kenneth Anger, Stan Brakhage, Michael Snow (well ok, Waters may have been reigned in for Cry Baby! 
).
For me it is a bridge to far to think that a director on set working with actors, a DOP and cinematographer and a massive crew to extract a filmed performance as money is ticking away should have any input from a producer whatsoever… wrong time and place!
Input that should be confined to the “daileys or rushes screenings” (probably even then it would be unwanted noise) but more appropriately part into the editing process.
