Why a torpedo that releases smaller torpedoes offers little advantage

Has anyone tried a cluster torpedo that releases several smaller torpedoes?

CAPTOR-like torpedo mines exist, but no torpedo releasing smaller torpedoes is identified. The proposed system offers little interception advantage and reduces the force available against a pressure hull.

Encapsulated torpedo mines such as CAPTOR provide a related idea, although a mine releasing a torpedo differs from a torpedo releasing several smaller ones. No example of the latter is identified. Once a torpedo has approached its target, splitting it into smaller weapons offers little of the interception advantage that might justify such a system in the air. A submarine pressure hull also takes a substantial explosive effect to breach. Keeping a powerful warhead together is therefore favoured over adding the complications of underwater submunitions.