I think both cases can be true. When I see TS codebases it’s mostly garbage for me but sometimes type annotation can help because you look into foreign codebase and see for example “this object has
items property which is array of
FooItem objects” etc.
So it depends. I don’t like TS and I think annotations usually clutter code, but yesterday I browsed some open source project and noticed that TS helped me understand codebase. It was like documentation.