I don't think you need WASM for that, I'm sure you can write a language that transpiles to JS and is still deterministic.
But WASM already exists and has many languages that are able to compile to it, why reinvent the wheel?
JS isn't deterministic in its performance
They tried their best: https://deterministic.js.org/
No, WASM is deterministic, JS is fundamentally not. Your dislike of all things blockchain makes you say silly things.