I think what he is referring to Gianluca, is a targeted question in his niche going to be beneficial because it is his username that links through to his profile, which is then the part that has the dofollow link.
To the Cesar - do you know if these support pages are crawled and indexed by Google? If they are, and the link from your username is not blocked, then yes, it could be beneficial.
Do you have a link for us to have a look at an example?
Andy