Five years ago no-follow links were introduced to combat comment spam. In the beginning all links were do-follow. It didn’t take long before blogs were being inundated by those who left insincere comments that added nothing to the discussion just so they could get a backlink, so no-follow links were introduced.
Today many blogs and content management systems, including WordPress, Blogger (Blogspot blogs), Typepad and most of the main blogging platforms have no-follow links enabled by default on comments and to change the links to do-follow links that pass PageRank action must be taken.
Meanwhile we hear the drama lamas who blog for money projecting the silly notion that the internet is full of no-follow blogs. In fact, nothing could be further from the truth.
Matt Cutts answers todays’ webmaster video: Will Google penalize sites which only link using the nofollow attribute?