Earlier quoted context omitted.
I think so. KaZaa was somewhat famous for implementing that feature using the non-cryptographically secure UUHash algorithm (instead of something like sha1) for better performance, which allowed trolls to insert fake file parts into your downloads.
I found a post talking about KaZaA and Napster, and that's right: I forgot but Napster had a central server to provide files, that's why it was so easy to shut down... https://computer.howstuffworks.com/kazaa.htm KaZaA didn't store the files itself so it was thought they wouldn't be possible to shutdown. From the site above: "While Kazaa claims to be "completely legal," there are those who disagree: The free-to-downl…
Gnutella brought peer-to-peer searches. Basically it used a flood-fill algorithm: your search would be broadcast to all connected peers, which would broadcast it to all peers that hadn't seen it yet, until somebody responded with the file and their IP and you could download directly from them. Interestingly Ethereum uses basically the same algorithm for block distribution, with some optimizations that were first published by RTM, who was one of the founders of YCombinator.
Kazaa's innovation was to split the peer space into "ordinary nodes" and "superpeers", with the observation that not all bandwidth links were equal. It would enlist hosts on high-bandwidth connections to form quasi-centralized indexing nodes to organize the network topology for all the low-bandwidth consumer nodes. It's a similar principle to how the Lightning Network works for Bitcoin, or how L2s on Ethereum operate. This also made it easier to shutdown than Gnutella though, because being a superpeer made you a legal target for the RIAA.