Hot take: the simple reason Gnutella declined is that it was replaced by Bittorrent.

Gnutella's original sin was that it combined distributed search with distributed download. In a rational world, that would be smart and good but in a litigious world, that was too sophisticated for the Supreme Court and they ruled it as infringing on copyright through inducement of the user. Gnutella clients, like other P2P clients with search, got sued out of existence.

Bittorrent offloaded the distributed search onto websites which routinely got sued or shutdown. Funnily enough, one of my big improvements to Gnutella in the first year of LimeWire was to drive out the website users because they were overwhelming the network upload capabilities without adding to them. That improved the 90% download failures in 2001 but interesting to wonder what if we had gone another way.

Sure, but the attached chat rooms were pretty handy, I used to like to download bootlegged concerts back in the day, to find new ones you've never heard of.

Plus, always fun to get laughed for mistyping The Almond Brothers Band at 3am...

I don’t think that’s a hot take, BitTorrent learned from Gnutella and made a better protocol. Gnutella is important historically, but it had a lot of downsides as a protocol that BitTorrent improved on.