Why navies accepted VLS despite the reload penalty

Why did vertical-launch systems take over from arm launchers if VLS is so difficult to reload at sea?

VLS offers faster reaction and a much higher firing rate, making it better suited to defeating saturation attacks.

The change exchanged magazine flexibility for immediate defensive volume. An arm launcher feeds weapons through one handling path, while a vertical battery can release many missiles rapidly. That speed matters most when an incoming attack threatens to overwhelm the ship's defences. Navies accepted the reload problem as the price of a more responsive combat system.