There is written But when you help someone find their Hidden Bandit, you do not get extra treasures, so there is no real incentive to help others find their Bandits.
The good of helping others. Comradery The general fun of co-op sillyness, especially with friends. Increased likelihood of quid pro quo. The joy of improving someone else's game experience. The long term benefits to the game of building and sustaining a friendly, helpful community. Etc.
