Well, the alternative to “Rust” here is not another programming language, but rather another game engine.
Because ultimately, most game engines will be implemented in either C++ or Rust, for performance reasons, and C++ itself isn’t terribly better at iteration speed than Rust.
The C++ engines have simply already invested decades into abstractions, like an ECS architecture, higher-level APIs and scripting languages. There’s nothing inherent to Rust which prevents these abstractions from being built into game engines, it just hasn’t been around for that long.