Had a thought. The reason throwing knives is such a useless technique apart from the ones already mentioned like having to retrieve them, is that when you throw them you spin them.
Spin throws are useless unless you're using the same knife from the same distance every time.
Combat throwers would probably throw no-spin, like competition throwers do. This video starting at 6:20 has a competition knife thrower hitting an ipad from 30', 35', and 40' with no-spin throws.