Were 40 mm guns designed for surface combat?

How important were surface-attack capabilities when 40 mm guns were developed, especially for motor gun boats?

They were planned and useful in that role, but surface fire was secondary or tertiary to anti-aircraft duties.

The weapons were recognized as capable against small craft, yet their design priorities centered on air defense. Their roles formed a hierarchy: break up attacks, kill aircraft that reached the inner zone, then engage surface targets. Larger naval guns should ordinarily have dealt with surface threats before they entered 40 mm range.