The porn fairy was, very often, more of someone quickly dumping something they didn't want found.
However, the really big piles were sometimes a person's little self-love spot away from their home, for one reason or another.
My grandparents lived adjacent to a big stretch of woodland. A half hour hike away from their house, and there was a run down old shack that had hundreds of various magazines. Just the slowly decaying stacks of playboy were astounding in number, and went back decades, though with plenty of gaps.
Best guess on that one was a specific gentleman that had owned the land, or his son. The overgrown path that was barely detectable led roughly towards their house. Considering the rather fiery and hyper-religious nature of the lady of the house, it could have been either, though if it was the son, he had picked up a lot of old issues at some point. Which, some people do.
But there were penthouses and hustlers too. It was kinda crazy.