In my experience it's amazing when you actually know everyone's job. Overtime as you progress in the manager's career you lost that ability. When that happens many managers struggle with confidence in the value they deliver.

If you take what you said about a ship and a team (which I take to) - each team member brings some value, which means that the manager can bring value even when they don't know the nitty gritty of all the roles. It took me years to get comfortable with that too.