Does anyone know why LEGO® uses the 3x2 black slope as spacers on their stations?

Hey guys, I recently bought two 60469 train station sets on sale here in Germany. I want to create a MOC with hopefully only using the parts of the sets, maybe adding some more from my collection. I want the MOCs style close to the modular buildings. So basically everything on one base plate. My idea was to add two track lines, with a middle platform where people can get in on both lanes and a platform at the entrance where people can get in the inner lane. To achieve that kind of layout, I...