I shop at Amazon as a Prime member. I comparison shop constantly.
There are quite a few things people buy from QVC that they cannot buy on Amazon, and sometimes, anywhere else. People don't always want something "just like" or "just as good as" a particular brand or line and don't want to waste time looking either. They want what they want, at the best possible price, the key word being possible. If you can only buy something you want at QVC it's a moot point.
You can find some of the things QVC sells on Amazon - some shoes, for example. I doubt you would find Linea, LOGO in your style/size, or Denim & Co. But what if they don't have your shoe size? You can order generic Xmas decorations anywhere or go to Big Lots or Hobby Lobby - but if QVC has something only they sell, you're not going to find it on Amazon. QVC doesn't sell razor blades or bird food, last I heard, so - apples and oranges. Amazon just does not sell everything that QVC sells.
That said, if QVC sells something that I can also buy on Amazon for a better price, of course I'm there. I've done it and I'm sure will do it again. Sometimes, though not often enough, QVC will offer a cosmetics, hair care or other deal that can't be beat anywhere, by a big margin, even with s&h.
Amazon is my go-to for most things because of Prime, but Amazon's and QVC's merchandise doesn't overlap as much as you think it does, for most people.
Life without Mexican food is no life at all