

Usually they give users points of credit to download more torrents: Users that don’t seed will burn through their download credits and won’t be able to download.
Other trackers will also give you points for every hour you seed a torrent (usually X points per gigabyte per hour) which encourages seeding even if the given file isn’t as popular, or so popular that other seeders choke you out of uploading to other users.
the thing with DMCA is that it’s super easy to issue one but potentially more costly to challenge, especially if your appeals to the host fail and your only option is court.
Hosts are scared of facing liability for approving appeals so they’ll just ignore them (unless the victim is a big name that can muster popular support) so as the DMCA victim you’re usually fucked