Citing a simple example. If the Symbiosis sect managed to slay Scarface Harry and the dropped loot was the Obsidian Fossil Anchor that Sheyan was wearing, would the Metals professor want it for himself? Definitely! But would he dare to keep it for himself? No! Because if he did so, all the close combat contestants who held the frontlines would be crushed, and the party would slowly disintegrate. No matter who wanted that object, it was given to someone who would need it the most. Even the commander in chief wouldn't dare to snatch it for himself.
On the contrary, if they obtained 'Ambition' such a mighty black grade weapon. Obviously all the close combat contestants would want to possess it. But in doing so, those far range combatants with high agility would start a riot which would already be going against the regulations of a party. To survive in this world, nobody would be foolish enough to go against the regulations, which would then cause the entire party to fall apart!