It is commonly said that the first thing an abuser tends to do is to try to alienate someone from the people close to them. This can be done in numerous ways, but generally includes things like telling someone that someone isn't good for them, keeping a person too busy to connect with others, and acting upset when someone spends time with others. It's an important warning sign that someone is dangerous, and it is vital not to break contacts with one's friends and family just because of someone else's prompting. If you really think breaking contact may be healthy and best, then it is good to get a second, objective opinion first, such as by discussing the matter with a therapist. But the point is abusers alienate people, because once someone is alienated, they don't have outside sources of information to give them perspective on their situation. Once someone is cut off that way, it is easy to manipulate their world view.
The exact same thing can happen on a different level with news sources or social networks. If you get encouraged to only use one source of news or one avenue of connection, then your information about other perspectives is being filtered out. It's easy to have a situation where you are led to believe almost anything, because all of your information comes from one source that can say whatever it wants. This is a classic Fahrenheit 451 or 1984 scenario.
This is why it is vitally important to actively pursue information about any issue you care about, and make sure that information comes from separate sources. For news that has more of a global impact, it can be particularly enlightening to read articles about the issue from multiple countries. Even if you only speak English, as I do, it is still easy to find articles written in English from many different places. A nice thing about the internet, is that it makes such research easy, and such articles tend to be conveniently available. For smaller issues, it often will not be covered by as many sources, but one can generally try to get a few different sources. If possible, try to check and make sure the sources aren't actually connected, for example, Fox News and Australia's News Limited are both owned by Rupert Murdoch's News Corporation.
The importance of multiple outlets cannot easily be underestimated. A person with two distinct social groups is likely to have better health than a person with only one. And a person with only one source of news can be led to believe anything. For one's own well-being and to be a truly informed person, do not allow others to limit you in your friendships or readings. On its own, it isn't enough to keep you from potentially becoming a victim, but it certainly does help.