That's a fairly arbitrary metric. The overwhelming majority of code running outside of the browser on my laptop isn't in Python, but it's hard to argue that's evidence of it being "doomed to being a second-class citizen on my desktop indefinitely".

> why webassembly is not used by the overwhelming majority of websites

This is such a bizarre take that I don't know whether it's just a trolling attempt or serious...

Why should web-devs switch to WASM unless they have a specific problem to solve where WASM is the better alternative to JS? The two technologies live side by side, each with specific advantages and disadvantages, they are not competing with each other.