JunFanJack, Judo's purpose is Judo, just as boxing's purpose is boxing and thaiboxing's purpose is thaiboxing. Some people aren't that concerned about self defence, they care more about the combative sport side of their training. Also I know practitioners of each of these arts who train soley in their chosen art and who have each successfully used their skills in self defence situations. Its nice to have different arts that specialise in certain aspects of fighting. Very very few people are experts in every area and having Judo(throws, subs), Boxing(punches, footwork), thai (kicks, knees, elbows), BJJ (subs, positioning) as different options means that its easy to get expert tuition in the area you want to improve. Have you heard of Georges St Pierre? He's one of the best fighters in the world right now, amazingly well rounded with no obvious weaknesses in any area. He attributes this partly to the fact that, rather than simply train at an MMA gym, he trains wrestling with wrestlers, boxing with boxers and BJJ with grapplers. Then a few times a week he trains in MMA to put it all together. Certain aspects of his game have improved drastically because he's training with people who are experts in those areas.