Have you tried doing that in C++? Doing that in a cross-platform way (or even in a single platform) is anything but easy, because you don't have a tool like cargo, you have to change your build system, do the dependency resolution manually, etc.
So no, such a library existing does not imply that using that is easy.
In Rust, you just need to write `cargo add unicode-segmentation` once in a project, and then you can directly use the library API. There is literally nothing else for you to do.
That's a pretty low barrier of entry, and something you will need to do 100s of times per project anyway, because the standard library is minimal by design.
If you prefer languages without a minimal standard library, then Rust isn't for you. Go try Python, where half of the standard library has a warning saying "deprecated: use this other better external dependency instead; adding this to the standard library for convenience was the worst idea ever and now we need to maintain all this code forever".
