I mean, it was all around the same time. But I would argue it was a correlative effect, not causative. People were already moving on to web based message boards

I mean, it was all around the same time. But I would argue it was a correlative effect, not causative. People were already moving on to web based message boards, more and more people were viewing Usenet as a place for warez & not discussion boards, etc. I'm sure there were people for whom that was the final straw, but I can't imagine that being the true nail in the coffin. Personally I stuck with Usenet until the early 2010's. But it was so low signal that in retrospect I'm not sure why I bothered.