If I understand the article correctly the argument is that ZD strategies don't do well against each other, so they can never dominate a population. Therefore th

If I understand the article correctly the argument is that ZD strategies don't do well against each other, so they can never dominate a population. Therefore they will not exist evolutionarily.  I don think that conclusion follows. I would expect the strategy to wax and wane around an equilibrium in which the proportion of other ZD players drops the value of the strategy to that of other good strategies. It's similar to many investing strategies that work well when a few people are using them but not when everyone is. These strategies never die, they oscillate from feast to famine.