The author's point is that predictive coding is a plausible mechanism by which biological neurons work. ES are not. ANNs have deviated widely from their biolo

The author's point is that predictive coding is a plausible mechanism by which biological neurons work. ES are not. ANNs have deviated widely from their biological inspiration, most notably in the way that information flows, since backpropagation requires two way flow and biological axons are one-directional. If predictive coding and backpropagation are shown to have similar power, then there's a rough idea that the way that ANNs work isn't too far from how brains work (with lots and lots of caveats).