The world of Hi'thron is a young world.
For a little backdrop understanding -- the world uses both the Western and Oriental elemental circles in descriptions of the world. This means that some cultures within the game ascribe everything to five elements (earth, fire, metal, water, and wood), while others only four (earth, air, fire, water).
Material Realm vs. Spiritual Realms. Everything in the Hi'thron world is based upon thought, feeling, and belief. Deities are powered, and indeed -- only exist as a result of shared belief. While a being may ascend to a state of god-hood; they only hold power so long as enough beings in the world continue to honor and believe in the deity. As a result, deities in this world tend to have smaller spheres of influence than in worlds such as Greyhawk. This also means that wars of religion tend to have an immediate and obvious impact on the powers of clergy and even the deities themselves.
The world is young, and as such, many areas of magic have yet to be explored. As such, mechanically there are no necromancy spells above 6th level. Additionally, much of magic is still waiting to be discovered -- with only a few of the world's key personalities hoarding the majority of the knowledge.