BECAUSE!!!!
My Unpronounceable-and-therefore-unresearchable Sensei's techniques can kick YOUR unpronounceable-and-therefore-unresearchable Sensei's BUTT!!!!
On a more serious note, though...I think that a large part of the proliferation of utter tripe, masquerading as Martial Arts, is due to our expectations as students. Very few people really NEED to be able to kill a person with a single, well-placed blow, delivered in a totally dark room, with a rolled up wad of damp newspaper. Or to tear an assailant's arm off and beat them to unconsciousness with it--
But everybody seems to WANT to be able to. Thus, you get every Thom, Chu, and Henri out there advertising that their system is derived from the Ultra Sooper-Secret Squirrel Style of the Hoo-Phuc-Yu Clan of Rambotronic Ninja, or that they've taught the Seals everything they know. Most of the traditional Martial Arts, it seems to me, encompassed more than just training to fight. They were a way of life.
Our instant-gratification seeking society is seldom willing to accept such a path. Instead, we want to be able to pick and choose from a modular smorgasbord of talents. We want to be able to fight like Bruce Lee, drive like AJ Foyt, woo women like James Bond, and earn Ted Turner's salary.
And the market obliges our throwaway wants with throwaway Martial Arts.
"Come on in! In just two years, if you're prepared to throw a couple grand our way, we can make you a stone badass!"
And people buy it. In droves. So, the next time you ask yourself why there are so many idiots and posers teaching Martial Arts, take a long look in your mirror, before you point your new $150 "Traditionally made, just like the Samurai used!" Katana at a sensei and call him a fake.
/rant off
Kal