The difficult is to know if that is a exploit or not. We have this knowledge often only when the developer say that is a exploit. In manual I don't find that is limited to one layer (I have checked). I see that is possible to put in building (indicated in User Manual) and often the building have many stage. We just build stage (same as we build a Castle). That is very difficult to know what is a exploit (designer of game doesn't want) and what is a feature. Example: I see that I can put some buff to others. That is a exploit or a normal feature ? In manual you don't see that you can set some buff to others and that is not indicated in tooltip). That is often why people indicate that is a nerf because he don't have knowledge that is not desired by the developer. Note: I don't use layer for planting, but I see this from long time, and I thinking that was a feature.