As some others here have said by now, Type 13 first saw a lot of use in the military, though others had already started using the lighter Type 7. The even lighter (as much as 4,000 lb) Type 8 started being used for chest straps too. This choice came from the fact that lighter Nylon webbing than what was designed for the hardware prevented slipping and twisting. While yes, Type 13 is for those worst-case-scenario jumpers who wish to have the absolute heaviest, it's not necessary to spend the extra cash if you determine a mix of types works better for you.
