The seed is programmed to send the tap root out and up and then down. The simple reason behind this (for those of you who believe in evolution) is that if a female plant drops hundreds of seeds, which is normal, then only the strongest survive. The catch-22 here is that the strongest seeds also have the strongest shell. So only the strongest of the strong make it. When the tap root is forced to grow up a bit and then down to take root, the shell of the seed is then in the position where the action and friction of the seed shell being pushed up through the soil help to break the shell open and then fall off. This approach allows the seedling to take advantage of leverage to get the shell off.
If the seed is planted with the pointed end down, then as it makes its way up through the soil, the action of pushing through the soil actually pushes the seed closed, and then once the seed shell breaks the surface, the last bit of energy your new seedling has must OMPH open the husk.
A seed trying to push open from the inside is like a small person trying to push a heavy door open from the middle of the door, rather than pulling it open with a handle mounted near the outside edge of the door.
In nature, if you drop a bucketful of cannbis seeds from a plant, more than 50% of them will land with the big end down and little end up - due to the laws of physics.
The preferred natural way for a cannabis seed to sprout is tip end/tap root end, oriented up.