In Chapter 1 of the book Reinformcement Learning An Introduction 2nd Edition by Richard S. Sutton and Andrew G.Barto, there is one statement "Exploratory moves do not result in any learning".
This sentence is in Figure 1.1.
Figure 1.1: A sequence of tic-tac-toe moves. The solid black lines represent the moves taken during a game; the dashed lines represent moves that we (our reinforcement learning player) considered but did not make. Our second move was an exploratory move, meaning that it was taken even though another sibling move, the one leading to e⇤, was ranked higher. Exploratory moves do not result in any learning, but each of our other moves does, causing updates as suggested by the red arrows in which estimated values are moved up the tree from later nodes to earlier nodes as detailed in the text.
It confuses me. In my understanding, exploration should contribute to learning in almost all RL algorithms. So, why does the book state "Exploratory moves do not result in any learning" in this case?