How is Ke$ha a Singer when she Raps more than she sings?

Nowadays in the mainstream, rapping and singing are becoming pretty much the same thing. Look at Wiz Khalifa. He's a rapper but in his song "Roll Up" he's crooning through half the song. And look at Flo-Rida he's considered to be a rapper but he's harmonizing in all his songs. Meanwhile Akon has always sang, but he gets labeled as a rapper. I think the line between rapping and singing in mainstream music have become blurred.