Labels play for certifications and plaques and of course Katy's payola crazy label would do anything to make Katy number 1.
When Def Jam and Big Machine Records updates the cerfications next era, Taylor and Rihanna will probably surpass Katy. But for now Katy holds that title.
Paradise was just a warm-up to the masterful greatness that is Ultraviolence. I don't mind not getting into it as much when I realize the full release studio albums are A++