IMHO, one major reason for the why: payment plans for most anything they sell. I can't think of another major (online) retailer that offers this, QVC has the infrastructure and risk all sussed out. Consumers can get moderately priced ($200-$500) goods in their hands quick for a fraction of the regular price and get them locked into a subscription-style model. QVC may have a much higher return rate than other retailers, but I assume they also have a higher rate of people who keep items they may not use or like and keep paying out of laziness.
Huh. Based on the OP article -- it appears that QVC places all risk (returns) on the [consigner] (interestingly the conjunction of {contingency}+{Signor}) -- and as such it would seem this is where QVC's limited risk is found...
Basically the equivalent of todays "Gimme your content and I shall provide EXPOSURE via my instagram followers"