undefined> The absolutely massive advantage of BitTorrent over older networks is that current downloaders (leechers) can share the parts they have already downloaded
This is not true at all. Bit torrent as protocol didn't brought any new concept to p2p. Bit torrent didn't invent download swarms or sharing while download (even the gnutella clients do that). Bit torrent won, because emule was ahead of it's time and was too greedy. The bittorrent block is 512KiB while the emule is 9MiB. Emule appeared in a time where ADSL was started to be rolled out, and before bittorrent, so the internet speeds and connectivity were not the best. Since the block is 9MiB, the users needed to download first 9MiB in shitty speeds before starting to share. Also people wouldn't realize that the network implements a credit system, so you need to upload (ideally to the person from who you are downloading from - the upload credits aren't global) otherwise you are going to the bottom of the download queue. This would cause a bottleneck in the speeds. Btw, emule continues to be used massively (not as bittorrent but more than 200k users)
here you have gtk-gnutella screenshots:
gtk-gnutella download progress bar: https://imgur.com/FIzJa1b.png gtk-gnutella upload options: https://imgur.com/yLg0LOl.png
Btw, gnutella died (it will never die because of the way it works, but it's a shell of what it was) because of the fake files (the DHT and magnet links appeared to late - with this the downloads can be curated), and because of the clients implementations. This last one was the gnutella downfall - There's the open protocol and then each client started to implement their own features making and giving priority in the connections between them, making almost subnetworks - kinda the same that happened with XMPP.
BTW 2, those slides are not up to date. The gnutella search as it is described in those slides are for gnutella 0.4. The protocol is now in version 0.6 (and probably won't be updated anymore) and it has now supernodes - kinda lika kazaa. Gnutella (mojito), emule (KAD) and bittorrent have DHT.