The part that everyone wonders, but can't bring themselves to say aloud for risk of sounding silly, is this:
Could the mode of thought of the ancients have been so alien to us, that (at least some aspects of) their minds are no longer comprehensible?
This isn't, after all, the only example of it. Jayne himself posited that a few millennia ago, everyone was some sort of schizoid puppets, lacking the capacity to have a will of their own.
This might not even be the sum of it. If they could be so alien, and thought in ways now incomprehensible to us, why then might it not be so that we too suffer similarly irrational ideation? Are there things important to us beyond reason, that seem to make all the sense in the world now?
Crazy talk. Stupidity. Incoherent ramblings. But that's why everyone wonders such silently, hoping the other guy will take the bait and suggest it...