What I took from that article was that, as a musician, spending too much time making youtube videos - posting stuff up on myspace music, keeping up with soundcloud track comments, &c... (those are my own examples of what I think he meant by online social media) harms your ability to focus, to create, and to ultimately cultivate a fan base that has a deeper appreciation for your music than the fleeting thousands that skip impatiently through a youtube video then go onto the next artist's video.
I fully agree, publishing yourself using social media is crucial - but so is doing live tours, shows, showing up to a random small beach party and playing some music (that will win you some fans), and spending time on your own creating...
That's what I got out of it, at least, please correct me if I misinterpreted.