Well, elemental and para elemental lords are fundamentally alien and distanced. Elemental deities fuelled by devotion and shaped by beliefs, on the other side are more closely involved. The paraelements are 6 because each element in this vision interacts with the other three, including its opposition. So Earth and Air makes Dust and Fire and Water makes Steam. Sun ( properly, Light) is Air and Fire, Magma Earth and Fire, Silt is Earth and Water and Cloud is Water and Air. This solution also allows the DM to have endless elemental cults, without involving directly a patron.