They have an obligation to report facts and world events, regardless of what they believe to be true. At least in a US context, the infusion of opinion and bias into news that CNN jumpstarted is a cancer that I feel is directly responsible for the highly polarized state of the US.
There is no avoiding the need for judgment in news reporting. Any process of judgement may be biased. An institution may itself have biases, and these will make there way in the judgments made there.
The idea that news organizations can simply and objectively report on facts and world events is functionally impossible. What you want are honest judgements made with an awareness of potential bias, knowing it can never be completely removed. As consumers of news, we should look for the organizations that seek to do that, and preferably read/view a variety of they present to us a more complete picture despite the differences in the judgements they make.
It seems like public discourse is by and large worse off due to the way news media is structured. In the drive for viewers and ratings, the media has become extremely polarizing. People make it a badge of pride that they don't watch X or Y network. You expose that a bit as well when you assume that the words I wrote should only apply to Fox. All cable news media is problematic in this day and age.
When I was young, I got into short-wave listening. This was during the Viet Nam war. I used to listen to the English language news from Radio Moscow, then the news from Voice of America, just for the sheer, rollicking entertainment value of the ideological whiplash. I suggest a similar exercise using modern context -- it will sharpen your BS detector.