One of the reasons for me personally is a rich selection of packages from crates.io. For example if you are writing a server in Rust, and use something like https://crates.io/crates/reqwest for http requests, then you can reuse it in your mobile app. Also there's serde. You don't need to write the schema for your data if you have Rust on both server and client. Just make a shared crate and use serde to encode/decode the data. It really saves a lot of time if you don't have to use swagger or similar tools. And there's a documentation out of the box with `cargo doc`