What if the great filter is not thermonuclear war or nanobot swarms, but simply this?
https://blossom.primal.net/10068408b126a115fcfaff048e6c6eaccb4bb407f25b4b4b2b3fd0daf8638c30.png
Civilisations get retarded before they get to make contact with others. Ooof. 😂