I'd debate that claim that it is fully relevant. Since I enjoy analogies the Bitcoin equivalent of that would be similar to someone making a bitcoin mining guide and starting that off with a link to "Buy my Antminer ".

The intention of the mining guide should be to teach people to mine and not to sell your product. But again as I mentioned the line between shilling and not shilling is kinda thing and difficult to effectively segregate here and going purely on the rules that are "written" I can see why it's allowed