Establishing a shared vision in product management is crucial for aligning the efforts of various teams. It's similar to a volleyball team having a unified game plan. A shared vision ensures that everyone understands not just the functionalities and features of the product but also its purpose and target audience. This alignment helps teams to work cohesively, with each member contributing towards a common goal. It's about making sure that everyone, from developers to designers, understands how their work contributes to the larger picture, leading to more focused and efficient efforts.