I think it's less "passion" and "focus", more his position as the Linux lead giving him first-hand experience with change control at scale. He didn't need a product manager to gather requirements, because he already knew them.
That's basically what ItsMonkk is saying, but I think it's worth making it more explicit. Because a one-in-a-million engineer is not replicable, but a deep understanding of your users' needs is.
Yeah, Rust is about the simplest language that guarantees both memory safety + low-level control. Almost all of its complexity comes from having to satisfy both.
I might be biased, as I'm the engineer that you're talking about, but that characterization feels unfair. Context-aware escaping is by no means common in the open source world—just look at Jinja or Handlebars. So unless you're knee-deep in an ecosystem that embraces it, it's easy to brush it off as unimportant.
https://doc.rust-lang.org/book/appendix-07-nightly-rust.html
It's a release train, similar to that used by Chromium and Firefox.
Edition releases (e.g. Rust 2021) are reserved for breaking changes only, and to retain Rust's stability promise, are opt-in.