Board Thread:Naruto Discussions/@comment-25498052-20141006092708/@comment-26302001-20141006224458

Plot no jutsu is the reason Nagato was stopped by being sealed and the reason he used Rinne Tensei in the first place. Same reason Kimimaro and Itachi died the way they did. When someone like Nagato, Kimimaro, or Itachi is too strong for everyone at the time of that fight, they either become good guys, die of natural causes, or sacrifice themselves all of a sudden. Plot makes it that there is always a reason why the main characters survive, or come back in most cases.