from a business perspective it is pretty easy to see, it helps otherwise totally unqualified buyers for these companies get closer to using actual amounts of raw material, it bolsters the accounts of these companies (especially mixed businesses like Saga that have b2b and d2c sales) during the off season where few sales are made, and helps them market to consumers when the season fever is still hot, vs trying to build a total ground up marketing platform for a new product in aug/sept.
but from a consumer perspective, i agree, its total shit. there is little to no ROI for what is essentially giving these companies thousands of micro-loans. You pay full retail, there are often shipping delays (again prob due to errors in the front office filled with a bunch of "your homies" who have never dealt with buying, ever), and they can put your money in the bank and kick around 3 to 5 months of interest.