Weird Erotica?

As the content of macrophillic, microphillic, and voraphillic(consumption of sentients or otherwise) goes, it brings about a difficulty in an attempt to create such works via other forms of media, given that the only possible media through which to express it vividly, given a lowly-budgeted source of funds, are computer generated models, hand-drawn images, and text. As such, it is not suprising to find that a main source of media for such fetishes to be compiled on a site which caters solely to said form. Coupled with the off-chance occurance that the initial development or period of development in which a vacuum serving to place a particular genre in quantitative dominance garnered writers, despite possessing a slouching verbosity and monotonous writing, whom actively cultivated something like the community you see before you in the abscence or sufficient excess of those of more loosely related genres, it seems plausible that by general spreading of word of such a development that it took dominance over this host of text-based media and constructed what you see today.

To sum it up, it's a combination of the scarcity possible manifestations of media avialable for said genres and mere happenstance.