How do you account for the story of the Sacred Band of Thebes, and elite unite supposedly composed of 150 pairs of lovers? While homosexual bonds certainly were an element of elite culture, they were not strictly limited to the class of the symposia.
Also, Alexander's men were hardly "the average Greek farmer" once his campaign was under way.
I think it's telling that it originally began simply as a legend of an elite unit and that the legend degenerated along with Greek life to the point where in the Hellenistic period a sexual element was introduced into the story - just at the same time as Greece was becoming debauched.
It's the same today - every historical figure who was not a notorious womanizer is nowadays retroactively portrayed as a homosexual.
This is true. But I still doubt that Egyptian, Parthian and Syrian footsoldiers were so much wealthier than their Greek counterparts that they could, almost each and everyone of them, afford a separate, kept boy toy.