So let's say I have a function that needs :name and :addr and it adds a new field calls :name+addr. Now in most (all?) statically typed languages I would have to say that this function takes a "name and addr" and returns "name, addr, and name+addr". So I have a type conversion, right? If the time comes that I need to modify these types, I have to do some sort of refactor.
In Clojure we'd just take a hash map and add a new k/v pair to the hash map we get. Any hash map will work, as long as it has the proper entries, and we'll just add a new entry to that. So if the time comes that I want to call this function with a "company" instead of a "person", it just works, as long as I have the proper keys. And to help check this sort of stuff we do have spec (https://clojure.org/about/spec).
TL;DR -- my belief having programed in both static and dynamic languages is that deep refactoring is primarily driven by the inflexibility of static types.