@tyil most browsers have native and efficient impls of the webassembly standard now. There's no transpiling into different JS, and both speed and size improvements made. If you have resource-intensive part of your web-app just implement in C, Rust or other supported language.
In terms of cramming everything in the browser I wholly agree: Please don't. Though I think with Wasm/WASI we get closer to a paradigm where we can ditch the browser. More local-first stuff, polyglot development, etc.