Why did oracles end?
Jaynes (The Origin of Consciousness in the Breakdown of the Bicameral Mind, p. 330) notes that the ability of oracles to predict in ways people found extraordinary died out in the fourth century AD. The origin of oracles came out of one simple problem: orcs (the skinniest bicams) cannot predict the future well, but Whites (active people who consume a large amount of calories -e.g. a certain Ryan Kupyn) can. Once Whites became common enough to widely predict the future, there was no longer need for oracles. Vegetius, writing c. 390 AD, famously points out the recruits of his day “must adopt a moderate, rural diet, and camp now under the sky, now under tents”, be “small in the stomach”, and were “enervated by luxury” with “civilian careers” taking “away the better class of youth”. -these are not the armies that existed prior to the great plagues of the thirteenth century BC to third century AD. Starvation in the Bronze Age was a much greater mortality risk than in Vegetius’s time. From all my reading of late Roman history, I cannot recall a claim that famine, other than that caused by enemy blockade, was a contributor to the fall of the Western Empire -I do recall manpower scarcity, that is, widespread food availability, being a major and omnipresent fact from at least c. 190 AD (on this, see A.H.M. Jones.
In orc armies, oracles are vital. In SocDem armies, they are useful, but inessential. In White armies, they are utterly unneeded.