If this person is conditioning their anecdata on "successful professionals," it's totally unsurprising that they'll find that successful professionals are successful. That doesn't help those of us who aren't lucky and need to figure out how to push ourselves over the threshold until our career catches.
(Note that I'm not saying that this person's success was simply the result of luck; they also had to be qualified and work hard. But out of the qualified people who work hard, not all of them can succeed.)
I don't know that I disagree with the author so much about social media platforms like Facebook per se, but I disagree with some implicit premise they're making.
The reason why things like blogs and social media presence are advertised so much is precisely because "value" really means something like perceived value, which depends on things like awareness. That is, it's not really so much whether or not what you do has value, its whether or not people are aware of you and perceive it as having value. So to get eyeball time, you need to put yourself out there.
I'm also a tenured professor, and what I increasingly see is popularity driving things, rather than value. That is, the rigor of academic work seems less and less important than the splashiness of it. The colleagues I know whose careers have taken off have done so precisely because they manipulate the social aspect of it--they're politicians more than scientists or mathematicians.
In this regard, there seems to be something disingenuous and dangerous about the general sentiment being expressed. To me, it generally seems to be dismissing the sociopolitical aspect of how we reward work, sweeping it under the rug, which will only worsen our problems.
But it is true. I'll save my criticism for things that are false, or utterly banal. And people at the beginning of their career might not fully realize how much things change when their career takes off. It's worth saying.