Indecently, the decline in the popularity of USENET makes it much less useful for anonymous messages; it's much easier to conduct traffic analysis amongst relatively few users/nodes [1] than it was back in the mid-to-late 1990's when USENET was at its peak and every ISP provided a feed. These days you will stand out if you have (or request) a USENET feed. Back then, it was the norm to have one.

[1] Yes, traffic volumes have increased (primarily due to sharing binaries rather than text), but the number of active users/nodes has certainly declined.