Intent doesn't actually accomplish anything. You can intend to kill everything all you want but if someone else does it for you, you are still leaching.
I think you are missing the point he is attempting to articulate. Two scenarios:
Scenario 1: Both players are attempting to gain as much gold and as much exp as possible. The groups split up, one team continuing to kill the enemies, one team clearing treasure rooms.
Result from scenario 1: both teams contribute and are rewarded from both goals: collecting gold and exp.
Scenario 2: one group of players is attempting to gain as much gold and exp as possible, the second group is unconcerned with gold, only interested in exp. The groups split up, one team clearing mobs, the other attempting to clear treasure rooms, but not always able to do so because of the speed of the mob clearing team.
Result from scenario 2: the treasure clearing room team benefits from the joint goal of exp, and from their additional goal of gold accumulation. The mob clearing team, however, benefits both from their goal, exp as fast as possible, but also from the goal they are not attempting, nor contributing to, and occasionally thwarting.