But if Hidan can't die, he doesn't need power on the level of Oro. Besides, we haven't seen much of what he can do, and the stuff we have seen is pretty powerful. If you're guaranteed a win once you consume some of your opponent's blood, what's your opponent gonna do? You have to stop him from hurting himself as well as from hurting you directly. Plus stopping Hidan's teammate(s) from hurting him - an easy stationary target. Given this one technique that Hidan knows, he has no need to learn any more powerful jutsu.