Ever since Fox News announced two weeks ago that it was parting ways with Tucker Carlson, its biggest star, speculation has raged about exactly which straw broke the network’s back. Was it the price tag to settle the Dominion lawsuit? The embarrassing texts in which Carlson privately disparaged Donald Trump even as he praised the president on the air? The video of Carlson mocking his own fans as “postmenopausal”? Still-unreleased texts in which he reportedly called a senior Fox executive a “c–t”? Rupert Murdoch’s dismay at the increasingly religious tone of Carlson’s commentary? Or (my preferred theory) some yet-to-be-disclosed act...