Below is a very good article that I suggest you read.
Now how many people on Influenster (moms and teens with fashion and makeup blogs, mostly) do you think have any idea WTF “nofollow” even is? Hardly any of them. Because they don’t know. Because it’s not an Internet thing, or a wordpress thing, or a blogger thing. It’s a Google thing. Google, with the same infinite wisdom (said with heavy sarcasm) that keeps messing up my Android apps, is dictating how we use the Internet, or trying to anyway. Situations like the one today with SocialChorus show that they are losing this battle.
The CEO of Social Chorus, Gregory Shove, said in an interview with Marketing Land:
“The bottom line is that we were not really focused or aware of this stuff until now.”
So a legitimate company, focused on their business, not caring about how they’re perceived by Google (which incidentally is exactly what Google says they want), didn’t know anything about “this stuff.” Exactly.
According to Google Webmaster Guidelines, “Another useful test is to ask, does this help my users?" Would I do this if search engines didn’t exist?
Well no, Google, I wouldn’t use nofollow if you didn’t exist.
Because it’s Marketing 101. Make cool stuff, get people to write about it and share it.