I'm still not sure that sequential downloading kills torrents. But disappearance of seeds certainly does. I recognize the problem of stratification, which is an inability of peers to trade. Stratification is a condition like this: Peer A has some fraction of the torrent, and has all of the pieces available on the network at the moment. Peer B has some fraction of A's pieces, and nothing more. Peer C has some fraction of B's pieces, and nothing more. Peer D has some fraction of C's pieces, and nothing more. Every peer has a different amount of the torrent, and none of the peers are capable of swapping pieces. Stratification would eventually happen in an environment where there is no seed, and every peer insists on getting pieces quickly in exchange for its bandwidth. If the torrent had sequential downloaders, the lower strata would tend only to have the beginning of the file. The higher strata would tend to be missing only the end of the file. If you see a stratified dead torrent with evidence of sequential downloading, it is easy to blame sequential downloading for the death of the torrent. But the torrent actually died from stratification. If the torrent does not have sequential downloaders, stratification can still happen. The only difference is that the downloaded pieces will look more scattered on each peer's map of the file. If a seed returns to the network, all of the stratified peers will be newly motivated to send pieces downstream because seeds reward peers for providing bandwidth. A torrent should not become stratified as long as seeds are uploading. It seems as if torrents need seeds, period. Peers that share while downloading will reduce the bandwidth burden on the seeds. But the torrent concept does not work unless seeds remain available. Well-designed seeds will distribute pieces to peers that are good at sharing. They will preferentially distribute rare pieces on the network. They will try to send the pieces to low strata, because this increases the number of times that the pieces will be copied as they "bubble up" to the higher strata through swapping.