So are disingenuous or just stupid? Of course society exists still, but what society?

Only the very dumbest think “doom” is some apocalyptic scene from a Hollywood film in which humans are nearly wiped out.

“Doom” is instead when swaths of Roman citizens with rights amidst a powerful, civically and technologically impressive hegemony, over time find themselves reduced to unfree serfs. They and their descendants would remain in that position for centuries until a horrific disease came through and killed so many of them that the serfdom became untenable.