I think it's the issue of the fact that they're selling so many different brands of products across so many different product lines (from fryers to washing machines to routers to laptops). So building the optimal sorting algorithm becomes an exercise for each and every line, and also involves standardizing the fields you receive from a variety of different manufacturers and distributors.

Certainly not an easy game, and definitely a tedious one. I know I'd hate to be on the team tasked with figuring that one out.