It's not even just Chart wise, which while important, is not solely the main criteria. It's a song throughly ingrained in the gen pop's conscious. You ask any person and they'll instantly know the song, even reciting the chorus.
Don't really understand how anyone can deny Beyonce's power. I mean she's been in the game for nearly 20 years, and she's still experiencing incredible success. She's an infallible brand, and she always be. Aside from RTW, she's never made a bad business move, everyone loves her.
