It's the same thing as custom ordering. They know how many exactly to order and won't have a large overstock supply to handle if they don't sell, and they only have to pay for the amount they order, not for excess quantity sitting in warehouses not being sold. This is most cost effective and many retailer's do this.
Also, sometimes these items are hand-made or made by smaller companies and they require a set shipment and have to promise a later day to ship, because they are made by hand and require time to be completed.
It's good for the vendor and QVC, and it helps us not to have to pay hidden costs for these ancillary expenses. So it helps keep the cost down on other products for us as well. Everybody is a winner. Just plan to have everything else done and wrapped so you can do just this closer to Christmas.