X>W>Z>Y is interesting. It’s similar to a PD, and so it appears that many of the same systems that evolved to enforce cooperation in PDs misfire in those cases and end up with Z (based on some observation, not any good evidence). However, unlike in a PD, Z is a worse outcome than the purely selfish X.
If a PD has the option to transfer value to your playmate and create more value, a XWZY (aka Deadlock) has the option to transfer value to your playmate inefficiently, so, in the inefficient state Z, both people are sacrificing to benefit the other, and yet each would be better off if the norm of sacrifice were not present.
X>W>Z>Y is interesting. It’s similar to a PD, and so it appears that many of the same systems that evolved to enforce cooperation in PDs misfire in those cases and end up with Z (based on some observation, not any good evidence). However, unlike in a PD, Z is a worse outcome than the purely selfish X.
If a PD has the option to transfer value to your playmate and create more value, a XWZY (aka Deadlock) has the option to transfer value to your playmate inefficiently, so, in the inefficient state Z, both people are sacrificing to benefit the other, and yet each would be better off if the norm of sacrifice were not present.
EDIT: All of this assumes 2W > X + Y.