There are several reasons for wax porting. It reduces unwanted mechanical vibration within the pickups components like screws, metal spacers, magnets etc. Another important reason is to keep the moisture from penetrating the coil and reduces moisture that could eventually cause the poles to rust on single coil pickups. Single coil pickups after time have a problem with Inner coil pole corrosion (ICPC). Waxing helps keep the insulation protected and if there ever was coil damage, it can be easily repaired. When using varnishes or epoxy potting solutions it usually mean the coils can never be successfully repaired without extreme damage to the coil or bobbin.