Things posted on social media can cause quite a stir and frenzy, especially if they are posted by a high-profile account. It is so easy to share opinions online that many people do it without thinking, causing many negative consequences. Whenever someone is angry, sad, or inebriated, they should take extra time to think about what they are posting, or better yet, don't post anything at all.
It's easy to justify angry words in the heat of the moment, but posting them on social media for everyone to see is a terrifically bad idea, as they're almost impossible to retract. It's better to step back and let yourself cool down before responding to something that makes you angry, in order to avoid saying or writing something you might regret later.
Social media might not be the best place to express yourself when you are angry, but it does give you some time to think and compose yourself. Other than saying something you regret there is no reason why people should not use social media when they are angry or upset.
The point of social media isn't to provide a sanitized image of yourself to the world. The point of social media is to get online and be social. Sometimes that means being angry and saying things that you might not have said otherwise. However, that gives your fans and the people that know you a chance to see your true colors.