reason: it is much more efficient.
"WebAssembly (WASM) is no longer a toy environment for cool demos. It's a thriving ecosystem that enables high-performance web applications with rich functionality. It's a portable code system that can run binaries in the cloud, or on your local machine. This may seem like an extreme position, but hear me out: if you develop a compiled library, language, or other tool you should consider making WASM a default binary target."