I can tell you that approximately one third of my articles started off as a comment , then then grew a life of it's own. I have a rule that when my comment gets to be more than one or two paragraphs, it needs to be a story of it's own.
I then write the story titled "In response to" blah blah blah" (whatever the title of their article is) . I immediately credit the original author in a subtitle and make sure I link to their article I am responding to as well as their bio. I almost always go back into their comments section and let them know I wrote a article in response to theirs. Hopefully it gives them a good feeling to know that their words have inspired someone else to write.
It has definitely resulted in some reads that I may never have gotten. Pay it forward in order to get paid.