As early as the 15th century, when the first stirrings of what might be called a more disciplined approach to history had begun, the story of Joan was being called into question. When the fable was used as anti-Catholic fodder during the Reformation, Catholic historians began to question its historicity. And soon, oddly enough, their perspective was confirmed by a French Calvinist historian.David Blondel (1590-1655) was a Protestant living in the Netherlands who effectively used the early tools of historical study to dismantle the myth of Pope Joan. Tracking the history of the popes during that period and the lack of any contemporary mention of Joan in what would have been, if true, an astounding event to be exploited by papal enemies, he dismissed the legend. His fellow Protestants of the era dismissed Blondel because, as Pierre Bayle said, "the Protestant interest requires the story of Joan to be true."
But the story is protean, so it persists. These days, it serves the secular agenda as an example of the supposedly "hypocritical" origins of priestly celibacy and the all-male clergy in the Catholic Church. The presumption is that such propaganda will cause the Church to change her practice in these areas. That's not going to happen, of course, but it will be an effective polemic in certain circles against the Church's moral teaching.
Eventually, the story will probably serve as the first combination foot ointment and salad dressing.
Twip! for your dip! Twip! for your do!
Curiously, I’ve read where the Benedictines are partly responsible for its popularity, finding a morality play in it. Presumably, they had no intention for it to be taken as true and as a slander against the papacy, but I do wonder their moral had been.