The default assumption for interpreting Google's actions is always that they want to close down communication channels they can't inject their ads into and/or can't control as a monopoly. Such that the fscking web with their millions of trackers dominated by G becomes the only form of digital communication possible. As happened with Usenet, XMPP, MMS, HTML/browsers, etc.
Google bought Dejanews and was an acceptable Usenet archive, for a time.
Then Google put the Usenet groups under the same umbrella as their proprietary groups.
Then their index became spotty (and you could retrieve some posts under groups.google.com, but not groups.google.de, or vice versa).
Today, Google Groups is near useless for Usenet.