typically it's not necessarily silencing, though pundits such as ben shapiro have backed out of debates with individuals who would challenge their policies.
undeniably, establishment hacks calling themselves "the solution" and "left-wing" who are also for the same institutions that conservatives support are blocking out the voices of libertarians and contrarians that challenge the system and won't hear criticism. in a sense, the so-called "liberals" are the conservatives that they claim not to be. i've said it time and time again, and i'll continue to say it: democrats and republicans are essentially the same
CNN once sent a guy out for calling out America's middle east policy which favored importing drugs from middle eastern nations and then arresting those who had possession of those drugs. not to mention how CNN and NBC will never ever call out donald trump for his record-braking drone strike numbers