You're right.

In practice (which happens often to any area) nothing stops a mentor from giving "boring" work to his apprentices, so that he could be spared to do something more exciting.

It's not ideology, it's just psychology. And the issue isn't how right you're, but whether you get your executives' buy-in and support.

(An anecdote: some people think "small, frequent deliveries" means they don't need to write as accurate a spec and development magically becomes easier--hence, e.g., testing isn't as much needed.)