I found it to be a very helpful post. I learned something that I can apply to my own site.
If such a post gets a few sign ups for planescape along the way, I don't see the harm. But advertising was far from the focus of the post. The author doesn't even say what planescape does.
The article wouldn't have hit the front page if it wasn't useful. How many companies are using retargeting + drip email effectively?