...is the modern equivalent of the old Victorian narrative that attempted to claim that women were inherently asexual and therefore "pure," since sexuality was considered something that tainted this natural purity. Chastity was one of the very few virtues a woman could have back then, along with the quality of her obedience to male authority. Women who expressed their sexuality back then were denounced, and the many who could not acknowledge their natural sexual nature used to claim that female sexual expression displayed by any woman was the result of a corrupting man "imposing" his influence and desires upon her (sound familiar?).
The same narrative has been modified to fit underagers today, just as the "slut" attitude continues to deride women who openly express enjoyment of their sexuality even as our society claims to consider it emotionally healthy as long as you are at least 18. Underagers, particularly girls, have taken the place of women in this emotionally-driven "purity" narrative. And it was quite astute of you to notice that "sexualized" is the modern equivalent for the term "whore," albeit applied to underage girls only, rather than females in general, as in the past.
This is how prudes deal with their inner hatred and fear of sexuality. They grudgingly claim to accept it when it comes to any group of people empowered enough to resist legal attempts to suppress it (which today amounts to anyone over 18, since they have their full civil rights), while fighting to suppress the expression of such desire by and towards a particular group of people who personifies the paradigm of purity that such people have such a powerful emotional need to preserve at any cost. And today, underage people--who lack most of their civil rights to resist legal suppression--serve as the ideal personification for this emotionally-driven paradigm. The plentiful evidence that the paradigm doesn't coincide with reality are rationalized away as being "imposed" from an outside influence. MAPs make an ideal scapegoat target in such a political climate, even though we are pretty much just collateral damage in the overall goal to stifle underage sexual expression in any possible overt form.