Jon Stewart helped crush CNN’s “Crossfire” in 2004, telling the hosts that their angry rhetoric was “hurting America.” Two decades later, Stewart’s protégé, Stephen Colbert, did just that with a combination of “fake news,” divisive monologues, and comic jabs at political enemies. Colbert’s “Late Show” signs off for good on CBS on May 21, to be replaced by a cheaper alternative — “Comics Unleashed.” The legacy media may be mourning Colbert’s exit, but many viewers see through the 62-year-old former Comedy Central star. Stephen Colbert’s “Late Show” signs off for good on CBS on May 21, to be replaced by...