I think using a well-chosen reward distribution is necessary, otherwise POWER depends on arbitrary choices in the design of the MDP’s state graph. E.g. suppose the student in the above example writes about every action they take in a blog that no one reads, and we choose to include the content of the blog as part of the MDP state. This arbitrary choice effectively unrolls the state graph into a tree with a constant branching factor (+ self-loops in the terminal states) and we get that the POWER of all the states is equal.
I replied to this point with a short post.