The randomness of the board set up partially cancels the bias you introduce into the dice. There are 20 different possible numeric token layouts, and each of t

The randomness of the board set up partially cancels the bias you introduce into the dice. There are 20 different possible numeric token layouts, and each of those has trillions of different possible tile combinations. You really have no practical way of knowing in advance which resource tiles will be under the number tokens you have biased for by loading the dice. So cheating in this fashion doesn't really provide that much of an advantage over the other players. Since the intentional cheating is scientifically indistinguishable from randomness, all good players will already be able to compensate for unfavorable variations in die rolls.