I think it's a negative, because people start spending mindless hours, and hours on it. Which gives me the advantage in life. Even if it's small. If I was a high school students, than my GPA would be higher than average, because I would refuse to get distracted, while my classmates do. That's the logic.
The downside of approaching social media with abstinence is that you are giving up participating in a key part of culture and society. I think that if you learn to discipline and limit your interaction with social media you can have the best of both worlds; you can keep your distractions limited and succeed elsewhere in your life while continuing to learn from online culture.