If I understand correctly, taking ronsimpson's example, if I insert a 3K2 (or similar) series resistance on the secondary (240V) side no current limiting resistor would be needed on the primary? I assume that is the point Nigel is making.
However, that raises a question in my mind. Why does the primary side of PA transformers incorporate 4 and 8 ohm windings, apparently to match the amp's output impedance, if the current is intrinsically limited by the secondary?