Zeppelins have a significant advantage over gyrocopters, for example. They have a significantly higher load-carrying capacity, which allows them to transport fairly large loads. For example, you cannot transport the Doom Anvil using a gyrocopter. No single gyrocopter could lift such a pile of metal, and multiple gyrocopters could not move in sufficient synchronization to safely transport such a load. Zeppelins can make the Doom Anvil a mobile means of strengthening Karaz Anchor's defense system. Imagine what would happen if all the Anvils could be instantly transferred to the aid of any besieged settlement? This is a colossal increase in the forces defending against any attack.