I don't think the RIAA's efforts had much effect on Usenet, since in that time-frame the RIAA all but ignored Usenet. They were much more in shock-and-awe over

I don't think the RIAA's efforts had much effect on Usenet, since in that time-frame the RIAA all but ignored Usenet. They were much more in shock-and-awe over Gnutella (https://en.wikipedia.org/wiki/Gnutella https://en.wikipedia.org/wiki/Gnutella) at the time. What I think led to the decline was at least a combination of: 1) an overrun of SPAM - Usenet was first to be hit by the spam flood, email SPAM came later as Usenet usage died off. 2) the 'newness' factor and the 'new shiny object' factor of the web drew away existing users, and resulted in new users never joining (i.e., pictures, fancy formatting, etc. all made plain text character Usenet posts look "old-fashioned"). And once you have a situation where new users don't join, and some number of existing users continue to depart, you are on a downward slope to disappearance. Both of the above helped contribute to ISP's dropping NNTP service. Bandwidth costs for #1 (plus bandwidth if they were carrying alt.binaries.*) and a drop in NNTP usage due to #2. They (ISPs) no longer saw offering NNTP as a sales factor for obtaining subscribers, and once NNTP was no longer a "hook" to bring in subscribers, it was only a matter of time before they decided to just drop it entirely. And of course ISP's dropping NNTP accelerated the issues around #2 above.