Why is dofollow better than nofollow?
Not only does nofollow fail to stop spam, it denies honest commenters and site participants a small but important reward. A normal dofollow link is a nice reward to a person who contributed a thoughtful remark on your site. Making your site dofollow, telling others that it is dofollow, and rewarding commenters will motivate more visitors to spend time on your site and provide valuable comments.