The cost comparison emphasizes personnel rather than steel alone. Removing a turret eliminates the gunhouse team and the larger chain of ammunition handling and support behind it. On interwar and Second World War ships, machinery spaces and turrets were among the largest concentrations of crew. A compact cruiser can therefore save substantial recurring manpower even when its headline combat capability appears only modestly lower.
Notable Point · 2:12:24-2:13:12
Deleting a turret also deletes a large crew burden
The Arethusa debate reveals why one fewer turret can materially reduce peacetime manpower as well as displacement and cost.