From the episode:
It’s funny how we sometimes expect that other people will know exactly what we’re thinking. We also assume that we know exactly what other people are thinking.
Think about when you were in the military. Every aspect of a mission was communicated from the officers down to the lower enlisted. Everyone knew what the objective of the mission was. While you could probably get the mission done with just the higher ranking soldiers knowing the full plan, the lower enlisted soldiers would likely start making assumptions about what needed to be done to accomplish what they assumed was the overall objective.
The same goes for communication in other areas of your life. Talking with your spouse, kids, neighbors, friends, or co-workers all require the same degree of attention.