The 4-inch pleating translates into a larger surface area of filter material, which in turn means the flow rate per area is reduced. So you have the same amount

The 4-inch pleating translates into a larger surface area of filter material, which in turn means the flow rate per area is reduced. So you have the same amount of air going through 4x the area of filter material compared to a 1" filter. Its analogous to using a thicker wire with the same current.