Routing of flightplans needs to be to the correct center. This is the center you would call to locate your flightplan if you knew the center telephone number. For flightplans that depart from airports, the center the flightplan needs to be routed to is always known as it is published in the FAA database NASR, so flightplans will go to the right center. But, if you file from a point that is not an airport, such as a VOR, a named fix, a latitude-longitude, or a fix-radial-distance, the surface boundary is important for the filing program to know so it can route the flightplan accordingly. If it goes to the wrong center, it is simply discarded by the center who in turn sends a rejection message back to the filing system. In some filing systems, this simply results in ATC not being able to find the flightplan when the pilot calls for their clearance. Usually this only affects IFR pickups after a VFR departure and pickup the flightplan when airborne, down the road. It would also potentially affect departures from farmer's fields, or a seaplane or amphib lake departure, or an accident scene by a helicopter.