By cherishing what is valuable to the other the gift transaction embodies the similitude between the parties. Alternatively, the gift-giver offers a gift that is of no value to him but is much appreciated by the gift-receiver. That is another way of acknowledging the recognition of the otherness of the other, and thereby making them the same.
The scope of that similitude (who gets to belong to the group that is 'the same') defines the scope of the decision-making unit. The action of gift exchange is for the sake of reinforcing the institutional character of the corporate decision-making unit.