My take on this concept is that when a horse is first started, having a job to do can assist a horse to get comfortable with just carrying a rider and following some direction.
I believe that training should involve working through as many challenges as practical to help a horse cope with life as a horse. For this reason, I will even invent challenges that have no practical purpose just as an excuse to grow my friendship with a horse.
I want my beginner horse to learn to have confidence and feel untroubled by following the pressure in contrast to going away from pressure or being sent somewhere in response to pressure.
I try to watch as many horse people working with horses as my busy life permits. In particular, I am always interested in observing other professionals to see what they do that maybe I could adopt or do better.