In 2016 this polarization didn’t just mean that Fox became steadily more pro-Trump as he dispatched his G.O.P. rivals; it also meant that a network like CNN, which thrives on Team Red vs. Team Blue conflict, felt compelled to turn airtime over to Trump surrogates like Jeffrey Lord and Corey Lewandowski and Kayleigh McEnany because their regular stable of conservative commentators (I was one of them) simply wasn’t pro-Trump enough.

The depth and breadth of Trump skepticism among right-wing pundits was a pretty solid indicator of his unfitness for high office. But especially once he won the nomination this skepticism was often filtered out of cable coverage, because the important thing was to maintain the partisan shouting-match model. This in turn encouraged a sense that this was just a typical right-versus-left election, in which you should vote for Trump if you usually voted for Republicans … and in the end that’s what most G.O.P. voters did.

My own CNN experiences were positive; I admire the many fine journalists who work in television news. But it was clear enough being in that orbit in 2016, as it should be clear to anyone who watched Trump’s larger relationship to his television coverage, that the business model of our news channels both assumes and heightens polarization, and that it was ripe for exploitation by a demagogue who was also a celebrity.