Alien civilizations already existing in numbers but not having left their original planets isn’t a solution to the Fermi paradox, because if the civilizations were numerous some of them would have left their original planets. So removing it from the solution-space doesn’t add any notable constraints. But the grabby aliens model does solve the Fermi paradox.
Alien civilizations already existing in numbers but not having left their original planets isn’t a solution to the Fermi paradox, because if the civilizations were numerous some of them would have left their original planets. So removing it from the solution-space doesn’t add any notable constraints. But the grabby aliens model does solve the Fermi paradox.