I don't think the comparison is accurate. The subproblem explanation of DP immediately lends itself to a strategy for solving problems: come up with a brute force solution then look for where you are duplicating where, i.e., how can a hash table help me? Even if there is a more efficient way to do things in the end than a hash table, I find it easier to go from brute force, to hash table, then finally look at it and see if I can optimize it further.