I think it boils down to the culture of those kinds of sites, which reportedly encourage an elitist secret club type of mindset over one which encourages preservation or dissemination of information.
The mindset cultivated seeders with the fear of getting kicked out if one was a bad peer / leech; ratios, bounties and freeleech items created a gamification for uploading material and seeding otherwise unpopular items for other users.
This appears to be the precise 180 degree opposite of what the case is as at 2 January 2017.