You will note from the photo of Iowa firing a broadside, that she has wooden decks. This is actually teak stripping laid on top of the steel, very, very expensive, but its about the only wood that will, untreated, stand up to exposure to sun and salt water. Impractical, too. They must be removed and stowed below during wartime because of the splinter hazard if the ship takes enemy fire.

But the admirals love their wooden decks, and they love to see their sailors on hands and knees holystoning them until they are bright amd sparkling. "Tradition", they call it. That kind of thinking is just one of the reasons I didn't stay in the Navy.