According to the updated article on Medium's distribution standards, stories written about Medium are disqualified from distribution. However, that doesn't prevent folks in the Partner Program from earning money on these stories if they set them as eligible to do so. A "selected for you" member-only article specifically about Medium was at the top of my feed this morning, and it’s not even by a writer I follow. So even if Medium isn't promoting these "meta" stories, they're still getting seen and still, presumably, earning money.