Earlier quoted context omitted.
I'm not involved in those, I merely use them for obvious reasons almost everyone uses them - network effect. Facebook is the XXI century rolodex (also, I was very young when I got on it, and it looked differently then); LinkedIn account I maintain for the off chance it could be useful in finding a job. Also, that doesn't mean I like how these services work. I fortunately avoided being ever involved in anything direct…
It is almost like your are advertising yourself on these networks. Couldn't people just find you from word of mouth?
A LinkedIn profile is technically an advertisement, but it's not one I push on people. Someone needs to go and look for it to find it. It's akin to an entry in a product catalog. I consider this kind of advertising to be fine, and I said so in the article.
(Also incidentally, all the jobs I ever had I got through the word of mouth.)