"In my experience, the more information is encoded in the type system, the more effort is required to change code."

Have you seen large js codebases? Good luck changing anything in it, unless they are really, really well written, which is very rare. (My own js code is often a mess)

When you can change types on the fly somewhere hidden in code ... then this leads to the opposite of clarity for me. And so lots of effort required to change something in a proper way, that does not lead to more mess.