When covering an entertainment event, events happens on-the-go. And you, as an editor, want to publish your updates to the internet (and your followers) as soon as possible. Creating a news item for every happening isn't worth it, but obviously, wou want to be the first to update people. You could use Twitter, but then you would only reach your Twitter followers. The same account for every individual social media network. You also want to read their comments, and probably interact with your followers.
You want to be able to publish updates from your laptop and phone, to your website and your social media accounts. You also want to be able to add photographs, taken with your mobile phone, and follow your socials in the meanwhile.