I was trained to remove the stylet once the tip of the ett had passed the vocal cords, then advance the tube slightly farther. Even if the stylet is not protuding from the end of the tube, the rigidity of the tube/stylet combo may scrape the tracheal wall. To be honest, I don't have any evidence for this, but it has always made sense to me. And I agree with your point about the type of provider, this is irrelevent, and the anesthesiologist was otherwise distracted. However, it is possible to intubate and remove the stylet at the appropriate time without an assistant.