1. Mass media brings power, the people who run that media have no incentive to even attempt to be neutral if they wanna keep it that way
2. Even if they wanted to present neutral viewpoints, such a thing does not exist. You never have all information – so the best you can do is go for something fact based and be very strict about the verification of these facts. And a ton of things are just not knowable at all. Staying fact based and not using emotions to steer people is a waste of your power (see point 1)
3. Even if there was a "neutral" viewpoint, neutral for whom? When I as an European for example watch the political discourse in the US I can't help but feel the "center" of the discourse is relatively far to the right in comparision to what a typical European would consider "neutral".
If you roll out universal persona that talks to everybody, the natural consequence will be that it will take on a different face depending to whom they are talking to, just because this is what maximizes the resulting power. I probably don't have to explain why such a thing would be deeply problematic on many different levels, but unless we solve the reason why people running mass media even have incentives to seek power with it this is the reality we are going to go into.