Firstly, what is Web Assembly?
There's a good answer on the Mozilla website here.
"WebAssembly is a new type of code that can be run in modern web browsers and provides new features and major gains in performance. It is not primarily intended to be written by hand, rather it is designed to be an effective compilation target for low-level source languages like C, C++, Rust, etc."
- frees up hardware
- frees up developer time
- reduces overall system complexity
- reduces time-to-market for changes and new developments
- reduces end-to-end latency