It works like this: Hardcore base voters want to watch media that confirms all their priors and then some. —> So fringe media outlets get traction with Republican audiences. —> GOP politicians need to go on these media outlets in order to reach base voters. —> The more politicians go on these fringe shows, the more mainstream these outlets become. —> Which creates competition for right-wing news outlets that are one standard deviation more sane, forcing those media outlets to get crazier just to stay on par.