@zoji3k red the topic again and maybe you'll get what op means, the term collection is being used as a synonym for "dump", with dozens of files that are totally unrelated or simply share a category, like twinks, or bears.
One thing that all those torrents share in common is that the files are massive, it might not be a "nefarious" reason but it is pretty much clear that they're doing it for the traffic.
IMO it only clutters the site and, if anything, makes it harder to find legitimate collections. But no one's forced to download, and it's not against any rule so...
Smile and wave.