As usual Our dear Lord uses parables to explain the deepest mysteries. One of these primary mysteries is that about the Kingdom of God that he has been inviting everyone to join. From the very beginning of his public ministry he vectors everyone there by repenting. He compares this Kingdom to a mustard see that mysteriously is able to sprout and grow from being a tiny seed to a big tree with branches that provide shade and security. We may not understand why the Church legislates this or that, or we may find such rulings as exaggerated and fanatical and so forth but as it is the Kingdom of God is a place where you can be secure from the dangers outside her fold. These rules are simply like what our parents used to give us to keep us safe at home.