It is all about ratings people. If you can get them they will pay you! She gets them and there is nothing wrong with her show. CNN doesn't because they want to make personal political points.
FOX show model is pretty simple in most cases. The most popular political show ever is CNN's crossfire. Where each side gets to make their point passionately without fear. That is the FOX model. The other networks gate their conservative guests, controlling the output in most cases. FOX says let it rip.
That is all they ever did in the prime time slots. If you are a democrat fire without fear of job loss. Only dems could/can do that on those other networks or you end up like Lou Dobbs. Pretty simple really.