In my opinion webtorrent hardly qualifies as a proper bittorrent implementation due to the limitations of webrtc.
It cannot interoperate with existing bittorrent clients.
And it cannot maintain decentralized networks, i.e. it needs a central rendezvous server and session tokens, bittorrent needs no such thing due to the DHT.
Currently there is no single entity that could be ordered to shut down a bittorrent swarm. With the need for rendezvous servers on the other hand you could order them to block specific content.
> For all practical purposes BitTorrent needs trackers for initial peer discovery
It does not. I have downloaded many DHT-only torrents. Startup time tends to be a little longer, but that's mostly because implementations are tweaked for low packet per second rates and not low latency, which in turn is somewhat related to the poor quality of many home routers which do not deal well with the UDP traffic.
> so it's not really much of a downgrade.
Since people are trying to decentralize the web recentralizing already decentralized protocols seems a huge step backwards to me.
> Even with a DHT for any kind of practical content discovery, sites would need to track at least one member of the swarm so new peers can join.
In bittorrent the DHT is not about content discovery, it is a global network which you only need to join once (contacts are persisted - something not possible with webrtc) which can then be used for peer discovery for individual swarms.
It cannot interoperate with existing bittorrent clients. And it cannot maintain decentralized networks, i.e. it needs a central rendezvous server and session tokens, bittorrent needs no such thing due to the DHT.
Currently there is no single entity that could be ordered to shut down a bittorrent swarm. With the need for rendezvous servers on the other hand you could order them to block specific content.