Disqus links

I know there are exist some threads on it, but they are old.
So my question is - do Disqus backlinks affect SEO? Google indexed them, I found in search and official FAQ also said it. The text of the comment is fully visible, but the link is going through a redirect. As far as I remember, google in 2012 begun to index JS.

Besides, what's confused me - Alexa rank is still displayed links in Disqus as indexed.

There are some sellers on here who do linkbuilding services who include Disqus within their packages, so they must think they work.