What webassembly provides is a bytecode format that multiple languages can target, that isn't owned by a corporation, and that's intended (as per their own docs[0]) to run both natively and on the web (with browser vendors already opting in.) This offers benefits over native code tied to an operating system, existing bytecodes and VMs tied to a specific language or company, and allows the possibility for applications to seamlessly operate on the web and offline.

The only thing a browser offers is an HTML and Javascript context... which are necessary to run it in a webpage, but not really the entire purpose of webassembly as a concept.

[0]https://webassembly.org/docs/non-web/

Sorta, I think go means “browser chrome” like the part isn’t the url bar and menus. Webassembly, assuming you use the browser engines, gets you some nice things sand boxing and true cross platform execution.