What makes you say that? People are actively earning phds researching implementations in different languages. JS is different because it’s useful? Runs in a browser?

React is pretty advanced under the hood. Just because it's Javascript doesn't mean you can't write advanced tech in it.

That's not academic research but that's R&D. And the React team has shown they're very thoughtful about what they're building.

It's been years since people were mocked for using Javascript. The language has greatly matured.