Do you know what is a nofollow?
It is a html attribute that can be added to links. That attribute tells to Google to do not follow that link.
That means that link will not count a backlink to your site. What means worse SEO.
This is very common in WordPress sites. It is a default config.
But here in Developer's Blog I want to share with you my links. I want to share my page rank.
I installed the NoFollow Free plugin. It remove the nofollow attribute from the comment author link allowing Google count your link.
Now every comment you leave here will be count as a backlink to your site 😉