Janelle - from Marietta, GA
The purpose of placing cake layers on cooling racks or grids is to allow air circulation completely around the cake. If the warm layer is placed on a solid surface (which either waxed or parchment paper would be on a cooling rack), moisture from the cake would build up on that surface, causing the cake to become damp and mushy. It most likely would stick to both the waxed paper and parchment paper.