Most ruby code isn't written like that - it's written like most static languages, where objects conform to interfaces / traits / type classes / pick your poison. The community is shifting towards explicitly specifying and statically checking types now. rbs and sorbet are a testament to this.
I wouldn't say it's really a beauty of the language, it may have been the original design intent but time has shown what's actually maintainable.
I don’t think the existence of a library to do something is evidence of the community shifting. For me the complete absence of types from any Ruby I see IRL or in examples from conference talks, readmes etc is evidence that the community is uninterested despite tons of effort from big players.