It's even worse than that.
Here, Google pulled one from the Microsoft playbook: embrace, extend, extinguish.
Google bought DejaNews, rebranded it into Google Groups (embrace) and then proceed to Googlify it, making it less and less Usenet-y and more and more Google specific (extend), until only the Google-specific mailing lists remained (extinguish).
Edit: see https://web.archive.org/web/20010226023947/http://groups.goo...