Back in the days, producers sometimes acted as dramaturgs. Saint Subber comes to mind. The playwright had to be cajoled, convinced, or bribed into seeing where the script might need revisions and focus. All of this would happen before rehearsals started.
Somebody acted in this capacity on virtually every play even if it was a spouse. They would have to gain the playwright's trust which is something Subber was good at. He is mentioned in several bios (McCullers, Capote) as being the 'dramaturg' although the term wasn't used.
In the best of all possible worlds, directors would do this, however in the commercial environment nowadays, directors are so overbooked that they might open one show on Thursday and start rehearsals on another Monday.
Our A list directors may do 6 shows a season: Doug Hughes, Dan Sullivan, Mark Lamos, Mark Brokaw come to mind although there are plenty of others. There is little hands-on, minds-on prep time.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher