Ruby is a language, not an environment. So why are you comparing Smalltalk environment to a language? (this applies largely to the original article as well - if you want to compare languages, compare languages; if you want to compare environments, compare environments).

There are Ruby environments that provide fairly deep introspection and live changes to a system, like Pry. It's just not the main way of doing things. For a reason: It's not the way most developers are used to working.