Part of the reason I'm somewhat convinced by this is that after reflection, the base rate for ancient Greece bring non western should be very high. We're separated by 2000 years + Christianity. Thats big.
Christianity emerged after a bunch of Romans decided to turn their failing secular republic into a cult. It did not stop the fall of their civilization, but until we reinvented rationalism a bit further up north and built a new civilization, we were pretty much that cult.