Social media is a bunch of things - entertainment, community, soapbox, message conduit, idea exchange, and often it is a source of news.
Most days makes a couple of hours of news. In the old days that got consolidated into an hour or two and delivered to you by Walter Cronkite, Peter Jennings, David Brinkley, Peter Mansbridge etc. into a concise report of the days newsworthy events. The 24 hour news channel didn't make more news, they just made them stretch 2 hours of daily news to fill a 24 hour time slot -- basically they use news as fuel for opinion, panel and commentary entertainment. With a few exceptions mainstream media has a liberal bias which can make it difficult for Conservative politicians to reach the public directly through the press - their messages are often filtered, spun, convoluted and sometimes just buried.
Trump could reach the harder right through FOX, but not always the middle and left. That's why he depended so heavily on Twitter. While Twitter the company is self stated as liberal, it's users base has less bias, they are across the political spectrum. For the most part Twitter does not interfere with messaging the same way mainstream media does.