What is Dharma? It is something intangible and hard to explain, at most we could talk only a little bit about it. Actually true teachings are not to be talked with mouth, and cannot be expressed with words. Therefore, it's not easy to teach the Dharma with this body or to spread it through physical means, because all physical things are already too coarse and do not belong to the level of wisdom. If we want to explain something that belongs to great wisdom with this non-wisdom vehicle, it is almost impossible.
Since ancient times, it has not been easy for any great Zen Master to come out and teach people or deliver sentient beings. They should fight with our habits and argue and battle with the conceptions that we are attached to. Not all people would come and listen every time when a great master comes out; even if some hear it, they won't believe it and even slander it after they go back. The slanderers, or those who won't listen, they only believe in their own conceptions. As in the ancient time, they didn't believe in the true teachings of great masters, but worship god of fire, god of sun, god of wind, etc. instead.
After an enlightened master passes away, he often becomes more famous than when he was living; because the King of Maya will use his name to carry out a plan of destruction, by turning it into a religion in which false teachings are mixed in so that people would think such is Buddhism and end up still a citizen of Maya, transmigrating still in the circle of life and death. He likes it very much; he will let us have a religion of comfort to "flatter" our longing for the true teachings, since many people want to search for the truth but don't know how and where to find it.