I would agree that I wouldn't typically hire a manager from outside my company if they have no previous time in that role, mostly because ramping up on all of the internal company structure, technology and processes is enough to keep people quite busy without having to learn how to be a people manager.
That being said, I feel the opposite about internal hires. One of the great joys of being a manager is coaching and mentoring the next generation of managers and having a healthy pipeline of candidates serves your company well.
The book What Color Is Your Parachute? recommended that people looking to make a career change do it in two steps: changing your job/role and then industry/company (or vice versa).
That being said, I feel the opposite about internal hires. One of the great joys of being a manager is coaching and mentoring the next generation of managers and having a healthy pipeline of candidates serves your company well.