Why heavy warships could not replace close-support craft

Why arm landing craft against tanks when battleships and cruisers were available offshore?

Heavy ships had the power, but close targets could be obscured or require faster reaction; destroyers and armed landing craft could engage from much nearer the troops.

Battleships and cruisers had greater destructive power, but they could not always respond quickly to tanks or strongpoints mixed with assault troops. Smoke, flames, terrain, and friendly soldiers could block fire from farther offshore. Destroyers and armed landing craft could push much closer, and some captains even beached their vessels to obtain direct shots. Proximity created its own danger because these small craft carried ammunition above the waterline and could explode rapidly when hit.