I should also point out that in many cases it wasn't adopted wholesale, for example Coptic (the egyptian language) was spoken by the majority of the population until after the muslim conquests.
I agree, a similar thing happened in Alexandria during Hellenism.

There wasn't anything inherent in greek culture that helped it spread
If I've understood correctly, then I'd also add that a lot of ancient literatures talk about the diffusion of Greek culture by the circulation of "artists", teachers and philosophic writings of Greece.