When doing probabilistic calculations, you can either use very, very precise representations of computable real numbers to represent the probabilities, or you can use various lower-precision but natively stochastic representations, whose distribution over computation outcomes is the distribution being inferred.

Of course - and using say a flop to implement a low precision synaptic op is inefficient by six orders of magnitude or so - but this just strengthens my point. Neuromorphic brain-like AGI thus has huge potential performance improvement to look forward to, even without Moore's Law.