In other words, it lacks the most important mechanism that lends dynamically typed languages like JavaScript and Ruby their power.
I think you haven't spent much time using Clojure.
Your phrase "it is more of a mashup of a few ideas from functional and OO languages" seems intended to downplay the language as nothing important. By that metric, Ruby and Javascript are both "just" mashups of lisp/scheme, perl, smalltalk and self.
Clojure can be just as dynamic as JS & Ruby. On the JVM, protocols are implemented in terms of Java interfaces, because that's how you get fast dispatch, however, protocols share little in common with "standard" OO. There's no implementation inheritance, a protocol can be extended to any type (except for a few limitations caused by the JVM, those limitations don't apply to other implementations, like CLJS).
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I think you haven't spent much time using Clojure.
Your phrase "it is more of a mashup of a few ideas from functional and OO languages" seems intended to downplay the language as nothing important. By that metric, Ruby and Javascript are both "just" mashups of lisp/scheme, perl, smalltalk and self.
Clojure can be just as dynamic as JS & Ruby. On the JVM, protocols are implemented in terms of Java interfaces, because that's how you get fast dispatch, however, protocols share little in common with "standard" OO. There's no implementation inheritance, a protocol can be extended to any type (except for a few limitations caused by the JVM, those limitations don't apply to other implementations, like CLJS).