Watch this video and more on Strategytraining.com
In this scene candidates learn a valuable lesson when using external, to the case, data/metaphors to make a point. It can lead to confusion and a loss of focus.
Michael shifts away from metaphors to think about the principles that drive a market-place monopoly. Again, Kevin is slightly rephrasing the question to help Michael.
There is a pattern occurring here. Kevin is never providing Michael with the answer. He constantly tries rephrasing the question to help Michael identify the insight needed.
Michael develops a critical insight by shifting from the location lever to thinking about critical masses in a market. However, he does not develop this insight further.