Usenet's failure is often attributed to the defaulting to allowing everyone and expecting users to killfile their way to a good experience, which doesn't work for keeping communities vibrant or dealing with spam. Hence, the decline of Usenet as alternatives opened up and Usenet failed to scale to Internet access getting wider.
Got a source? Having previously pretty much lived on Usenet and now not having fired up a newsreader in years - while frequenting reunions of two Usenet groups I used to be on, one on Facebook and one on G+ - I'm interested in anything written on the subject; I think it's one there's not enough well-written post-mortems of.
I don't think killfiles were a significant factor myself, but I admit I'm basing that opinion just on "it sounds wrong", not any actual data.
I'd have attributed the decline of Usenet and mailing lists to (1) not being on the Web (that's the biggie) (2) barrier to entry to create a new discussion forum (even alt.* had process). Mostly (1) - the wine-users list (for Wine, the Windows compatibility layer for Linux) has a two-way gateway to a web forum, and immediately the forum was available the volume was 10x.
I also posted some hypothesising as to why there are no good Web-based Usenet readers - and why forums aren't backed by NNTP - here, with a bunch of people I met on Usenet commenting. tl;dr that the unit of NNTP is the message, but the unit of forums is the thread. Same applies to mailing lists, which is why GMane seems weird considered as a "forum".
Got a source?
Not really. This is my own lived experience comparing Usenet to Google Groups, Reddit, web forums, and Wikipedia, and noting the explosion of user-contribution in the shift from Overcoming Bias to LessWrong. You could easily prove Usenet is declined, but I'm not sure what research you could do to prove that the incentives were structured wrong or that features like killfiles fostered complacency & reluctance to change, other than to note how all of Usenet's replacements were strikingly different from it in similar ways.
...I don't think k
Below is a message I just got from jackk. Some specifics have been redacted 1) so that we can discuss general policy rather than the details of this specific case 2) because presumption of innocence, just in case there happens to be an innocuous explanation to this.
So... thoughts? I have mod powers, but when I was granted them I was basically just told to use them to fight spam; there was never any discussion of any other policy, and I don't feel like I have the authority to decide on the suitable course of action without consulting the rest of the community.