We’re replacing protocols with Rust now?

This is it.

WebAssembly AFAICT is all about making existing code runnable in a JavaScript environment. JavaScript isn’t great itself, but Chrome provides pretty amazing tooling, so it’s good enough.

Add to that: if you want to write WASM in a strongly typed language, you need support libraries that define all of the browser primitives. If you’re an accomplished web developer, it’s more effective to stay in js.