It would, if there weren't episodes of RRP being too high at release, forcing retailers to discount immediately to generate sales. There have been many sets released, where people use the phrase "That's not a $60 set" or "That's more like a $** set". So, when the adjustment comes at the retail level to sell more, discounts pop up. It's similar to car manufacturers having to offer huge discounts on certain models because no one is willing to pay MSRP.
I get it's easier to compare sets when using original retail pricing, but it's much more complicated.