In my opinion, the main reason[1][2] for its decline in terms of text discussions was due to the deal that Andrew Cuomo (the attorney general of New York at the time) made with the major ISPs to restrict access to child pornography. This resulted in many ISPs discontinuing their usenet offering and cutting off their customers from it.
Unless those customers made an effort to access usenet some other way, they stopped using it.
Unless those customers made an effort to access usenet some other way, they stopped using it.
[1] https://www.cnet.com/tech/tech-industry/n-y-attorney-general...
[2] https://www.cnet.com/tech/tech-industry/cuomo-strong-arms-co...