It's understandable that the thought of this is daunting to so many people. They believe that it will be difficult to learn and take too much time. But really, it's so easy once you get into it. And while you do have to do some work, you don't have to spend several hours a day at it. You just have to be persistent, participating regularly. And the time you spend on it tends to fly, since the activity is often so enjoyable.
When you get down to it, social media is not so much work as recreation. It's just socializing online with people who share your interests, "shooting the breeze".
While ultimately your participation may have commercial goals, it's mainly about you as a person. Just as it's great for demonstrating that you know a lot about your field, it's also a way of showing your good character. That's why it's really important to have a decent photo of yourself in your social media profiles. Everyone you interact with will associate this with your activity which will definitely help make you professionally attractive to them.
The process is akin to what politicians do in building a public profile and gaining trust. While they are part of a team (unless they are independents) and must toe the party line, they must still be known by the electorate as living, breathing, unique individuals. They have to get out there and get people to warm to them personally to some degree. Otherwise they won't get elected. That's why they're always on the lookout for mainstream media coverage and are keen to present themselves as well as possible every time they do get it.
Given this, it's no surprise that pollies are well represented and very active on sites like Twitter and Facebook. They've seen the benefits of participation in social media and have embraced it wholeheartedly. While presidents, prime ministers and opposition leaders might be too busy to personally write all their updates and tweets, they'll still do quite a few of them. And most ministers and senators do control their own accounts completely. These are very busy people, remember. So if they don't outsource their social media work, surely those in business can do the same.