This came up in a conversation I had with a few friends, and it's worth looking into. Yerf used to be Fur Affinity, before Fur Affinity. It was the main art posting site for the Furry Fandom and had a major part in integrating fetish and fur communities.
There would be art challenges back in the day, were people would suggest things to draw for a few weeks. Now we had your standard things like dresses and fields, but there were also some… interesting suggestions, such as "why not draw characters eating each other like in the wild" or "why not make the characters really fat?". This would cause a flood of unintentional fetish art onto the site until someone realized that the guys that made these suggestions were into that "in a sex way". While most people ended up purging these images, some realized that they enjoyed making them, and this carried over when DA effectively made the site obsolete. The archive is still up for historical purposes:
https://yerf.metafur.org/yerfartists
Credit to Nemo on FA for helping me.