A year or so ago, I posted a link that you can help Anna's Archive by seeding their torrents [0]. I monitored (eye-balled) their stats [1] to see whether there was a bump in seeding afterwards, and couldn't see one. So, the "low conversion" comment might be true.
I don't think you can draw any conclusions from this. Maybe that the avg HNer does not have feel like allocating 500TB of space and bandwidth to host copyrighted material...
[0] https://news.ycombinator.com/item?id=40672215
[1] https://annas-archive.org/torrents