Very true. It won because it tapped into a simple but persuasive idea about interpersonal dynamics -- only be benevolent if your opponent is benevolent. It succeeded with this simple strategy against much more complex schemes.
Oh, just the opposite: tit-for-tat starts out benevolent and only retaliates when the opponent `cheats'. And tit-for-that is also quick to forgive.
Grim tit-for-tat, that keep punishing after the first transgression, and a tit-for-tat variant that starts out malevolent in the very first move (but then copies the opponent) did markedly worse than straight up tit-for-tat.
