Anthony is a product of the hobby industry and his success. It's often funny and disturbing at the same time that those who work in the commercial end of the industry never recommend NSW, but those in the service and hobby sides dont mind using or recommending it.
And to say that synthetic salt is perfectly consistent is pure bunk. They dont produce a product they cant profitably sell. To ensure that one batch matches another in consistency would be a major undertaking. They can make sure it is within certain standards or guidelines, but the manufacturer sets those points themselves.
NSW changes with the seasons, tides, currents and biology in the oceans. Animals not only expect the natural cycles, they depend on it to regulate their own biology. NSW will change gradually, where a bi-weekly water change with synthtic salt can vary widely.