Yes, that is what it is about. She insists on being generous, and she is! But I think there is a little bit of a compulsion there, other than the “wheeeeee! christmassssss!!! Time to buy shit tons of stuff!” Which is obviously a bit of a compulsion.
Parents of new new babies have exacfly the same problem, grandparents who load up their household with stuff at Christmas despite being asked not to. There have been numerous posts over the years here and elsewhere about that. To some people, this Christmas holiday is ALL about the piles of presents.