If there is one thing the nobles learned after the rise of the god of justice, it was to take over the pathway of knights. They learned that the pathway of knights was too powerful to leave in the hands of others.
The nobles are still killing any knight who doesn't have a noble family. They have decided to monopolize that power instead of eliminating it completely.
Of course, in exchange, they have to spend a lot of resources in order to cultivate an army for the pathway of knights to show its complete power.
The Ivory family hasn't reached that point yet. Only a rank 4 knight can gain power from an army of mortals and godclads of every pathway.
But once they reach that point, they will surely need a lot of resources to raise an army. Right now, those resources are going to the lamp bearers, who are stealing the resources and using them to turn the people against the nobles.