As far as I know it's because the Rust is filling in the gaps - two of the three articles are about relatively new features. And the next Rust release should close the stable/unstable gap by stabilizing some macro/compiler plugin stuff.
There was a flurry of Rust posts about "why Rust" near the end of the year, which was somewhat "coordinated". In the sense that Steve wrote a post and this triggered a chain reaction where all kinds of folks wrote about related topics. Completely unintentional, just happened. Most of those posts did not make it to HN.
No marketing plan involved, and nobody coordinates these posts.