[edghf]

I found the second link you posted when I went looking for clarification. The takeaway for me was that zero-determinant strategies do tend to win games, in that the end score of someone playing a ZD strategy is usually higher than that of someone playing a different strategy, but that both scores in such games tend to be low. Against a basic tit-for-tat player, the ZD player will win by a very small margin but the game will largely consist of mutual defections. Basic tit-for-tat, as the author points out, is never a 'winning' strategy--it always either ties or loses. Its strength isn't that it wins, but rather that it limits its losses. That characteristic of tit-for-tat is as effective against a ZD strategy as it is against any other strategy.