Apart from all the other things people are mentioning, I'd add that the development of Rust happens in the open. That means that a lot of very interesting debates are there on GitHub for everyone to read. For example, here's where arielb1 discovered that the original scoped threads design was unsound: https://github.com/rust-lang/rust/issues/24292 (which sparked a large debate about whether mem::forget should be allowed in safe code: https://github.com/rust-lang/rfcs/pull/1066).