Because Google made a popular interace to USENET called Google Groups, then added a non-USENET component and discontinued the USENET part. By doing so, a lot of people ended up on the non-USENET part.

A secondary factor was spam getting out of control IIRC.

Usenet still exists!

Yeah but free usenet servers with binaries are rare.

Binaries were the ( second ) death of Usenet. It went from being a social medium to the poster-child of copyright infringement.

I wish uuencode had never been invented.