Why the simulated battleships use heavy barbette armour

Why are the barbettes given so much armour in these simulated battleship designs?

Heavy barbette armour helps keep a turret explosion from sinking the rest of the ship and provides a way to redistribute weight in the constructor.

Ultimate Admiral: Dreadnoughts appears to apply the barbette setting to the vulnerable area around the mount, so light protection produces frequent early explosions. The later one-on-one battle adds that heavier barbettes can contain the damage when a turret blows up. Barbette protection also provides a practical way to move weight around a design in the game's constructor. The answer concerns the simulation's damage and weight model rather than a general armour prescription for historical battleships.