I adore Gaga, Britney and Rihanna but the majority of the images of them being posted are not yet iconic. Umbrella and Bad Romance are the only recent hits that could be considered iconic. Britneys only truly and generally agreed iconic moments are the kiss at the VMAs, the BOMT outfit and the OIDIA, anything other than those that people are posting are mainly the blindness of a stan.
It takes quite a bit of time for something to become iconic ordinarily.
People seriously need to stop pushing Bad Romance. I know it's a fan favourite but Poker Face was way more iconic and defining within GaGa's pop legacy.