The final nail in Usenet's coffin was the removal of the discussion filter from Google searches in 2014. Before that, people could use that filter to easily find others talking about something, but apparently that didn't please advertisers who wanted users to find only companies selling that something, so Google removed that filter and problem solved.

https://www.seroundtable.com/google-discussion-search-dead-1...

https://browsermedia.agency/blog/google-kills-discussion-sea...