I've listened to Rush's show off and on for years and while I have known him to take call from Democrats, he usually will only accept such calls if he can find something about the commentary to put down. Rarely, if ever, will he accept a call from someone who's position not only goes contrary to his point of view, but from anyone who's more factual than he is. Of course, what radio talk show host wants to be shown up by any caller no matter what side of the isle he's from? Of course, he and others like him have to cater to their base. Same goes for Liberal talk show host; but since I don't get Liberal talk radio shows here where I live, I couldn't tell you if they do the same thing in such mean spirited ways.
Maybe someone who does listen to Liberal talk radio jocks can elaborate and/or give their perspective. What I can tell you is of the Conservative talk radio host I've listened to - Rush, Hannity, Levin and Coulter - rarely do they take a call from a Liberal whose point of view they agree with even slightly. But I've come to expect that from them. Again, they're catering to their base. Is their commentary toxic? Let's just say they all tend to edge up to that imaginary line and hide behind free speech to obsolve themselves of being responsible for the level of anxiety they knowingly create. They want their listeners to get upset what what they consider to be wrongful decisions made by the Left even if half of what they report on found to be true.
But again, they're catering to their base. So, to them anything and everything they say is worthwhile as long as they can claim, "I didn't say take matters into your own hands except at the voting booth."