It's a feedback loop of adverse selection. They become more politically slanted, fewer people listen to them, their revenues plummet, their recruitment pool gets shallower, they become more politically slanted... At a certain point only true propaganda believers willing to work for ~minimum wage remain. Now, they're also getting hammered by social media hastening the process.

The same thing happened to communists. After 50 years only idiots and sociopathic opportunists (since they still had the spoils of power) could be found in the party.