playBunny: That doesn't make sense, there must be a point at which equilibrium is reached where players of different ability reach different ratings.

For instance if I win 62.5% of the time against a weaker opponent, we would balance out at a point where I stand to gain 6 and lose 10, whatever that difference is.

I agree in principle that this system is not good for backgammon, but the ratings would not balance to everyone equal since there is some skill in the game.