That argument doesn't really make sense. The type system is a feature of the compiler, so why would the output of the compiler need to be aware of it? Lots of typed languages compile to machine language, which has no inherent type system.

Compilers which do add type information into the output are usually paired with a runtime that uses it for things like late binding or dynamic dispatch, but JavaScript doesn't support anything like that.

Could you give a concrete example of a scenario in which the flexibility of the JavaScript type system would break the TypeScript type system?