Let me point out that Krav Maga has developed and evolved since being invented in the late 40s. All arts were invented by someone at some point to meet some perceived need by the creator of the art. Most systems taught today are recently created in a historic sense. Kano combined Jujutsu, sumo and western wrestling to create judo just over 100 years ago. 40 years ago, Bruce Lee developed JKD. He meant it to evolve based on his principles, but now you will hear people talk about "traditional" JKD. When faced with Mongols attacking in formation, the samurai had to adapt to survive. i feel that the martial arts should be adaptable, alive, and scientific. I remember being an 11 year old kid seeing Royce Gracie win the first UFC and saying, we need to learn that. And we added what BJJ we could get to our system that was already part Goju Ryu, part JKD, part Judo and such. So while I mostly disagree, I will say that Rex Kwon Do is just awful.