Apparently, there's some sort of hierarchical social structure, especially prevalent in anime uploads; basically people with higher "caste" would upload more popular anime.
I have heard of stories where those who are not complying these systems, or people trying to get out of the system (especially higher ranked ones) are shunned, either by giving anonymous tips to police, etc. (It has been rumored sporadic arrests being made by police, despite larger user base, are because of this.)