It was probably something like this: People upload a lot of stuff to their service. Once content goes "stale" no one is viewing it anymore, but they are still storing it. They decided they could either remove the material to make room for new stuff or monetize the old material in a way that justified keeping it around.

The cost of storage is pretty low so maybe I'm reaching a bit here on their behalf. I have no idea what sort of scale they are at. Perhaps I just like to believe that people aren't trying to be evil.