If a bunch of bimbos went to the National Enquirer and lied, and then the National Enquirer believed them... the bimbos don’t get sued, right? Only the paper?
That is correct, at least as far as the person libeled goes. That person can also sue the bimbos, but they don't have as much money or as big a megaphone.
Newspapers field all manner of claim coming from crackpots and cranks. It's up to the press to choose what it will publish.