Why? Medieval Europe at the height of the Medieval Period (e.g. near the peak of the Medieval Warm Period) had a population around 100 million, of which approximately 1-2% were in the priesthood. Add in Paladins, since in 3e they worked the same way but would not be classified as priests in IRL terms, and you probably get a minimum of 2%. That's two million divine casters, just for one corner of the world. Even if the world overall averaged only half of that (so 1% of population being priests), the estimated global population of Earth in 1300 was between 360 and 430 million, so 3.6-4.3 million divine spellcasters.
So yes. I stand by what I said. The surveillance theocracy would be crippling to actually doing anything.