From the 1950s until the 1980s, the regulatory scheme for TV was premised on spectrum scarcity. Since the American people as a whole owned the airwaves, they had a right to impose a public trust on the parties to whom they were leased. Part of the public trust was the Fairness Doctrine, which resulted in the exclusion of unbalanced and extreme opinions from TV. Every owner of a TV station was, in effect, a gatekeeper.
Technological changes made the concept of spectrum scarcity obsolete and ultimately led to the demise of the Fairness Doctrine in the 1980s. From that point forward, TV was treated as something similar to magazines and newspapers, even though, in reality, its pervasiveness and immediacy give it far more impact.
Today, in the real world, there are no TV gatekeepers. The business model for Fox News is to stoke the anger of reactionaries to a point just short of insurrection. There are no regulations prohibiting this; the Fairness Doctrine isn’t coming back any time in the foreseeable future.
The bottom line is that someone needs to talk to the Murdochs and persuade them that being the mouthpiece for violent reactionaries is going to blow up the country and cost them money in the long run. There is no other realistic solution to the Fox News problem.