That's the point. Suggested setup (editor with JS/TS language server constantly checking your code) means you will know about every problem that would possibly

That's the point. Suggested setup (editor with JS/TS language server constantly checking your code) means you will know about every problem that would possibly break something, you just don't need separate "source code" producing "build package". It means you can ship your code directly to target platform that only understands JavaScript. AFAIK that's not what you currently can do with TypeScript (except Deno).