The main reasons were that Swift supports OOP and Rust doesn't (useful because web standards are object-oriented and it's easier to follow the specs when you ca

The main reasons were that Swift supports OOP and Rust doesn't (useful because web standards are object-oriented and it's easier to follow the specs when you can model them in your code), and that Swift supports C++ interoperability instead of just C interoperability like Rust (makes it easier to incrementally move to Swift in an existing C++ codebase).