Commenting from no-follow blogs

In my previous post, we say that no-follow sites are not good to juice up your link in order to get your site improved in the search rankings, however it will guarantee you to receive traffic from targeted visitors in your niche on blogs, forums, software sites, etc. People say that if we comment on no-follow blogs, is it useless for them in terms of search optimizing. But they really don't know that they are still able to receive traffic with them. No-follow blogs are still useful for traffic purposes only.