Another useless piece of kit to rust, which serves no purpose at all.
In the wet, any water is thrown off the disc & hub in much the same way as a spin dryer works.....it's called centrifugal force. In addition, any crap that lands is also thrown off as there are no nooks and crannies for it to get lodged.
The rear backplates however are different as the brake mechanism is mounted on them.