The Kademlia network (eMule, Kazaalite, etc), did indeed use a global P2P Distributed Hash Table, to resolve which IPs hosted which content, which the torrent protocol also does … some of:
Unlike the mainline torrent protocol, Kademlia’s DHT (like the modern-day Tribler DHT), also resolved filenames to content, allowing in-app search.
With torrents, one needs to consult a DHT crawler, or an index site (which sucks; centrally operated sites are fragile, compared to DHTs), whereas eMule & more contemporarily Tribler, have two layers of DHT, enabling decentralized search without relyiance on someone having created a listing at some particular site & that site being online to search its index.