Why armor remains useful against shaped charges

Does the existence of shaped-charge warheads make battleship armor pointless?

No. Layered armor and subdivision can limit how far a penetrating attack reaches, preserving systems and crew even when the outer protection is breached.

A weapon's ability to penetrate armor does not remove every benefit of protection. A shaped charge might enter one compartment without reaching the next. Another armor layer and subdivision could keep the attack away from vertical-launch cells or engines. Losing an outer space and some auxiliary machinery would then leave more of the ship working. The aim is to make damage harder to inflict and contain its consequences.