Didn't see a lot of HN posts about "How one rewrote Y from Z to Rust" yet.
Basically - Go had a very strong focus on web servers from the start, making it easy to pick up and develop web servers with. Web developers make good early adopters - they'll pick up new tools faster than almost any other group of developers. Rust was released without any of those tools, and they're still changing as the ecosystem develops (especially around async frameworks). And even with that, there's a fair few companies using it for all sorts of cool things: https://www.rust-lang.org/en-US/friends.html