JSX is expensive than JS, because JSX first needs to become JS, then other things happen

There are a bunch of server side apps that turn JSX into static HTML with no JS. It’s just a template language that compiles into JS but you can do anything with it you could do with other template languages.

That doesn't speak to this comment:

> Not sure why everyone wants to write a programming language inside HTML like lit does

When that's exactly what the OP's suggestion of React does.