From the introduction "Compiling programs into JavaScript, asm.js, or WebAssembly with tools like Emscripten or GopherJS isn't enough to successfully run many programs client-side" it seems like the intent is to be able to port "Unmodified C, C++, Go, and Node.js programs" to the browser.
I think the parent poster thinks this is somehow breaking out of the JS sandbox (which it's not).
> (Just don't put it in production lol)
Why not? If you were to use multiple "processes" using Browsix in your app, it actually may be _more_ secure as Web Workers do not share state with each other and the main thread. (EDIT: Although for me I would at best take inspiration from this rather than use it for a real app)
Big use case for this I would imagine is games