I'm not an expert at this, but this is what the RFC says: http://www.bittorrent.org/beps/bep_0046.html http://www.bittorrent.org/beps/bep_0046.html >The inten

I'm not an expert at this, but this is what the RFC says: http://www.bittorrent.org/beps/bep_0046.html http://www.bittorrent.org/beps/bep_0046.html >The intention is to allow publishers to serve content that might change over time in a more decentralized fashion. Consumers interested in the publisher's content only need to know their public key + optional salt. For instance, entities like Archive.org could publish their database dumps, and benefit from not having to maintain a central HTTP feed server to notify consumers about updates. You are technically right that the torrent file is immutable, but basically this lets clients know that the torrent is updated using the DHT data. The outcome is the same.