Note that some journalistic organizations have strong rules on social media use[0]. Not to mention many unwritten ones. Interacting outside the bubble could come with repercussions. I'd wager that if you'd look at people in other public facing professions you'd get similar results.
[0] Example: https://www.ap.org/assets/documents/social-media-guidelines_... "However, friending and “liking” political candidates or causes may create a perception among people unfamiliar with the protocol of social networks that AP staffers are advocates. Therefore, staffers should try to make this kind of contact with figures on both sides of controversial issues. "
In an ideal case they should be able to express their opinions and people wouldn't extrapolate them to the respective employer.
Journalists not able to express themselves freely because of guilt by association would be a huge problem and being able to do so provides extra information that can put articles in context.
Another fact worth mentioning is that large publishers all have a direct business relationship with social media companies, primarily Facebook I believe. Some better newspapers were transparent about it and lamented this fact as a necessity in the current news market.
Thanks to companies generally having no backbone and disciplining employees for social media use or generally for their opinions, we are at this bad situation. If they just had ignored the complaints...
All that said, the opinions of the most outspoken journalists often seem very predictable and in many cases they actually argued in favor of accountability by social media use by writing their outrage articles about some random tweets. I think a lot of those have missed their profession... Didn't take disclaimers like "opinions are my own" too seriously, but apparently they might be needed for some journalists at least.
This seems like extremely wishful thinking. Say one silly thing, or something that could be interpreted wrong, you could lose your job from an indignant mob.
Some big journals also punish open disagreements and fights with other writers writing for the same journal. I am talking about the guardian or new yourk times here.
[0] Example: https://www.ap.org/assets/documents/social-media-guidelines_... "However, friending and “liking” political candidates or causes may create a perception among people unfamiliar with the protocol of social networks that AP staffers are advocates. Therefore, staffers should try to make this kind of contact with figures on both sides of controversial issues. "