Good to know. Worth pointing out that the C++ standards committee also almost never breaks backwards-compatibility. Instead, they just introduce The New Way (and then The Old Way becomes just one more trap).
If you're in a position to affect this for Rust, it's worth thinking about. Give the documentation and libraries a few years to catch up, so that we don't have to chase a moving target. Maybe focus more on compiler and toolchain optimizations, and less on language features.
It's a little rough to play in an ecosystem where the language itself effectively has a nightly/unstable variant.
That's very much been the theme of 2019 and 2020. 2019 really only saw the introduction of async/await as a new language feature. Almost all other additions were smaller things, like "this feature expanded a bit" or "this edge case is no longer an edge case." There was only one instance of something straight-up replacing the old thing; mem::uninitialized by MaybeUninit.
We are not changing the language in backwards-incompatible ways.