Rust's philosophy (unlike Python's, for example) consists in not including tons of stuff in the standard library, this way you can choose the best implementation for your specific use case from one of the many crates (which are super easy to install, by the way). There is no "always the best" implementation for a specific functionality, nor a legacy-but-still-officially-supported-in-std implementation that nobody uses anymore but still needs to be maintained with its own namespace.

I don't see this as negative or "reinventing the wheel". Reinventing the wheel would be writing your own implementation, which doesn't happen if you can choose from many high-quality crates.