The vast majority of the spam content is injected into these newsgroups via Google Groups itself, and is not even seen on other NNTP servers.
Blocking posting access to these newsgroups from GG is generally a good thing for those newsgroups.
Not being able to search the archive is the unfortunate collateral damage though. Google is not obliged to provide a Usenet archive, I suppose.
Formerly obtained deep links to the content also do not work!
If you formely cited a comp.lang.lisp article by giving a direct link into Google Groups, people navigating it now get a permission error.
What would be a good free NNTP server or NNTP archive?
The D programming language forums work as a NNTP server as well as web forums. I have in the past downloaded all content from the forum allowing me to have fully offline archives of threads. This is so underrated. I think NNTP could make forums much more superior although it feels like there arent many clients springing up AFAICT.
Adding some new NNTP features to Thunderbird was my introduction to open-source software and ultimately led me to being one of the primary maintainers.
NNTP is a wonderful protocol, arguably the simplest of the 4 mailnews protocols (IMAP, POP, SMTP, and NNTP). While it seems to share the same basic format as RFC822 messages, it actually tends to avoid some of the more inane issues with the RFC822 formatting (generally prohibiting comments and whitespace folding).
Unfortunately, the internet by the early 2000s started turning more and more into an HTTP(S)-only zone. Usenet itself hemorrhaged its population base, especially as ISPs shut down their instances (e.g., because someone found one child porn instance somewhere in alt.binaries.*).
Vladimir Panteleev did, though, write a web interface to NNTP:
which is also freely available: