We’re laying the ground rules for Israelite society. Last chapter law and government, now religion.
The priests are to be supported and honoured as full time ministers. They have no land, God is their inheritance. And prophets will continue Moses’ role of speaking the words of God.
This is compared to the occult practises already rampant in the land, and there is reference to why they are so detestable, child sacrifices etc.
They have the voice of God, they don’t need to consult the dead or search for truth by elaborate divination rituals.