Yeah, exactly. I worked for a small employer in the early mid-90's who maintained a NNTP feed (and had for years), and ultimately had to shut it down because it had basically become a giant unmanageable firehose of porn and piracy. The actual human-written text content had dropped down to the 1% level or worse.

Usenet died for the same reason Facebook won: people exploit "free" forums in ways that ruin the experience. It's simply not possible to have an unmoderated discussion environment in an unrestricted internet, which is why we're having this discussion on a moderated site.