Or not just a factory, but a nursery. What if being advanced beyond biology didn't eliminate the creation of new energy forms, but they found they realized the best way to maturate their children was to contain them in 'vessels' or body containers. Yeah, they own the entire universe- and earth is just nursery out of a trillion- and the collective unconscious that Jung proposed, that's Universal wi-fi that all beings can access.

Star Trek: TOS 'The Metamorphosis' or maybe we are them, taking on bodies because we so love this species it was one for us not be alone...