I was also running a news server for my school and an ISP around the same time (1994-1996). The alt.binaries hierarchy was a constant headache. The total data flow and storage requirements were already about 10X the rest of Usenet. We had to manually tweak refuse lists when the disk drives filled up.
I wasn't still around, but I expect the second wave of automated binary posting/retrieval tools in the late 90's probably created the surge that changed Usenet access into a separate paid service, no longer something that came with an ISP account like email.
However, it wasn't just warez and porn that killed Usenet. Spam took off there before email, and it wasn't until email spam became untenable that modern automated filtering tools were created.
Why did you have to include alt.binaries.? I thought the alt. hierarchy was basically optional, and it was the news server admin's prerogative to opt in and out of alt.* groups.
I wasn't still around, but I expect the second wave of automated binary posting/retrieval tools in the late 90's probably created the surge that changed Usenet access into a separate paid service, no longer something that came with an ISP account like email.
However, it wasn't just warez and porn that killed Usenet. Spam took off there before email, and it wasn't until email spam became untenable that modern automated filtering tools were created.