It's a thread about who has a bigger impact, not who sells more. Besides, take of her U.S sales and she's just barely on par with Rihanna on a worldwide scale. And that's not counting Rihanna's singles sales.
The girls started bringing up sales so stop chiming in. And let's not pretend that sales is not one of the indications of an artist's impact. When people are getting your album on the first week like crazy that's when you know you made an impact to the GP somehow. No one's doing it nowadays but Taylor so let's not. And why would you take out the sales from the US? You can take out Rihanna's sales outside the US and it would be terrible. It goes both ways so..
Let go had a bigger impact than rihanna's entire career
Where is Avril now though? No one is checking for her outside of forums like these. The same would be said for Taylor if she stopped making music or suddenly flopped. Facts are facts.