Maybe Jack should have been more careful. If Jack started to prey on players who did not know how to protect themselves then Jack should be punished. Either by the other players or by someone in a position of authority.
But I don\'t think your post was about PvP. Its about favoritism and how it will be more widespread in a free game. I agree with you, but I think people need to get something out of all their hard work, and being able to help a friend out is a nice thing. Especially if they want that friend to keep playing with them.
I know it sounds selfish, but think of it as a cleric praying to a deity for divine favor. Or a child crying for its food. Those people have the ear of the person in the position of power. And when their is a petition for favor, the likely hood that it will be granted will depend on how much the authority agrees with, gets something from, or likes the petitioner. Also how much work the authority has to go through inorder to grant the favor is involved in the decision.
I say, trying to eliminate favoritism is impossible. Changing and limiting it is not.