At long last the secret that has been hidden from true believers has been revealed; the nymphet models for this provocative display of flesh have legs so long that they are virtual infinitesimal parallelograms.
That being so, the fact that they can wear crotchless panties is demystified to some extent. In other words, they have nothing to hide, so why waste material by covering an area that ain't there? Or as Gertrude Stein said about Oakland, "There's no there there."
In this era of transgender sex composites, what could better exemplify the complex nature of sex than someone so sexless that they have no erogenous zone? It is not difficult to imagine that in the near future, having no sexual identity whatsoever will be so Zen-like that crotches will become obsolete.
What goes around, comes around.