Why is a rib outlined with object lines and not hatched in orthographic sketches?

In orthographic sketches, a rib is outlined with object lines instead of being hatched to clearly distinguish its edges and shape. Hatching is typically used to indicate areas of solid material or sections in a cross-sectional view, while ribs are often represented to show their dimensional characteristics without implying additional material. This approach helps maintain clarity and ensures that the rib's geometry is easily understood in the context of the overall design.