Teachings that were right for different individuals
The Buddha realized that different beings had various capacities, so out of his great compassion and skillful means, he gave teachings that were right for different individuals. Although the essence of the teachings is to simply let be in recognition of ones own nature, the Buddha taught a lot of complex instructions to satisfy people on all different levels. Another reason why there are the nine vehicles is because people couldnt leave well enough alone. It seems to be human nature to love complications, to want to build up a lot of stuff. Later on, of course, they must allow it to fall into pieces again. ~ Tulku Urgyen Rinpoche