Gifts serve social and political purposes and are not simply a medium of economic exchange. Historically, gifts were a way of signaling surplus to gain trusted

Gifts serve social and political purposes and are not simply a medium of economic exchange. Historically, gifts were a way of signaling surplus to gain trusted friends, establish status, make alliances, compensate victims of wrong-doing and squelching the rage of would-be enemies. The loss of efficiency and the wasted resources are precisely the point. "I have enough to destroy my own wealth for your benefit" was, for most of human history, the way to gain status in your tribe. Productive and occasionally generous people became leaders. In modern western culture, the mutual holiday gift exchange may not seem like it has much to do with status - but then why do we open gifts in full public view rather than retreating to separate rooms to open them in private? There is clearly a family/social dynamic at play that goes well beyond economic exchange. You could even re-frame the "waste" of gift giving as an investment in social infrastructure.