Comment by tonyg

No, not necessarily. Various Smalltalks have a wide range of different approaches to UI and IO more generally. This (their "operating system aspect" https://eighty-twenty.org/2019/01/13/why-learn-smalltalk) is the area in which they're most diverse, in fact. For instance, GNU Smalltalk has, by default, only a REPL, while Smalltalk 80 has a bitmapped GUI.