You're supposed to be writing from experience - experience with people, with reading, seeing some homeless guy on the street and making up some story of him in your head. If you never see any of that or have those conversations or even sleep enough to have vivid dreams, then what are you writing about?
When you're the showrunner, you're the person that's in control of most of the details, and to be able to take all that and then to step right behind the camera and to have a direct line of communication with the crew and with the actors - to not be delivering that through another person - is pretty freeing and extremely stimulating.