It is not original to note that while it is women who do most of the complaining about how much food there is just lying around, begging to be eaten at the numerous Christmas festivities, it is also women who organize 90% of it and bring 90% of the food. Ditto the small cute objects exchanged, followed by complaints about how cluttery the house is and how out of control it feels. If women ran the world, we would spend a great deal of our time exchanging small presents and feeding each other snacks.
It's easy for men to criticise and complain, I suppose, because we don't have the instinct/training.
I think this is another one of those tribal thingies. While training and social grace are clearly part of this, the universality of it suggests some biology in the mix. Interestingly, while it occurs everywhere among women, it is not universal among women. A large percentage of women think this is how life should be, another group goes along with less joy but recognising some obligation, and a further group actively dislikes and resists the custom - especially that small gifts part.
But if you work in a situation that is predominantly staffed by women, as both my wife and I are, half your house becomes filled with plates of cookies, small decorative items, and written greetings. The other half is filled with similar items that the women of the house are preparing to go out of the house, to communicate to some other friend or family member that you, too, do matter. You are one of the tribe. My wife compared it to potlach ceremonies of the Pacific Northwest.
It may be one of those instincts by which women make sure that everyone in the tribe has something to eat, and some declaration of group acceptance is signified by making sure that no one feels left out.