I wasn't officially involved but I did cruise around the periphery of many music warez groups and Efnet IRC channels from the late 90s/early 2000s, and I agree that it was a very fascinating time. Groups like RNS, EGO, KSI, REV, CMS, WHOA and countless others from back then.
Early on it used to be very open. You could join, chat, go in the bot room, download whatever. Get friendly with a few people and maybe get invited onto some private FTPs with no waiting. I found out about them by searching the group tags in the filenames of music I saw on Napster, learned how to IRC and I was in there.
Some of the stories/beefs groups shared in the nfo files were wild. One of the weirdest ones I (vaguely) remember was Cam'ron's SDE album, it was leaked onto the internet 6 months early and allegedly was stolen off a bedroom dresser. Something like that.
It was thanks to those groups that I could hear the original versions of Ghosface Killah's Supreme Clientele and Bulletproof Wallets, when the CDs I bought in the store didn't match the tracklists on the packaging! I loved the really rare stuff. It wasn't why I originally got involved but it was mainly why I stuck around for a while. Ultimately it wasn't that long in hindsight, because around late 2001 almost all of the music channels kicked everyone out and went private, supposedly there was a crackdown scare and people were covering their tracks. I got spooked and never went back.
A buddy of mine stuck around though, and kept his connections tight. To the point that the people he stayed close with all still keep in touch today in a Facebook group, where they still discuss how to get music free despite access being easier than ever. Old habits die hard.