Determinism! [0]
I'm switching a browser game side project from Typescript to WebAssembly because determinism enables a simpler style of multiplayer. Instead of relying on a server to manage state, I can just send inputs p2p like a modern fighting game (with rollback [1]). Then the game acts just like singleplayer! For a hobbyist like me, WebAssembly makes the minefield of multiplayer so much easier to navigate.
[0]: https://github.com/WebAssembly/design/blob/master/Nondetermi... [1] A blog post on rollback netcode (not in wasm): https://ki.infil.net/w02-netcode.html