It makes sense with Sol, because he came into existence to define and give form to the Ebon Dragon, which is pretty much exactly what a fetich is. It makes far less sense with any of the other gods.
We also have gotten some expansion (I'll see if I can dig it up) on what the Charm that the Primordials used to keep the gods from directly attacking them does. Basically, that geas only applies if a god directly attacks a Primordial. If one of the Primordials attacks a god, that god has the geas lifted from him for a day. Also, Malfeas can lift the geas. Hence why, say, the Primordials never took out the Incarnae in the Primordial War.