The order knew that myths needed to be implemented into the world in order to avoid arising suspicion. The word myth has become the only way for humans to be able to buy into the lies that are told to them. The order never allow for humans to be in contact with creatures that are considered to be part of science fiction. The reason for this is that the humans would try to exploit those forces by attempting to wage war against their enemies with them.
A lot of mythical creatures could end up being used by humans. The reason for this is that some of them are wild and not smart enough to be rebellious. This is the reason why the order was careful enough not to allow any of them to be exposed to humans. They are all safely confined in special structures that humans will never be allowed to access.