The one about medium meta content is simply untrue, because it’s visible and it shows behind the scenes these are the posts that get the most distribution. When you look at how well those posts get distributed, the internal distribution is way higher than the external one, and it’s way higher than for other posts that are about different topics.
If I publish about medium itself, the article will get strong internal distribution, but if I publish about something else, it’ll get distributed less. So unfortunately, this is just not true.