Olly, you are right, professional growth depends on a person. The motivated person continues to grow professionally under any circumstances. But what if these conditions are very comfortable? It’s like you are trying to wake-up early in the morning for the jogging. You don’t have any desire to leave your warm bed.
Would you agree that it’s much easer to get out of bed when you are jogging together with like minds jogging lovers as you are? They will get you out from the comfort zone to achieve results. The same role can play an external design team for in-house product designers. They will motivate and inspire them to create excellent products.