Well, I don't understand how Britney could ever hype her material if she didn't write it

Even though I do not condone Gaga, Kesha, or Nicki making these hyperbolic statements, it is easier for them to get there because they craft their own material. A lot of people involved in their own work tend to feel proud to the point of exploiting their own material, for better or for worse. Good marketing strategy, but it does set standards too high. The best changes in music seem to be unplanned.