Modern languages like Rust/Go/Clojure typically incorporate polymorphism without the need of inheritance and get more out of it rather than less. The type of polymorphism and malleability you get from Clojure is much more expressive than class inheritance.

You're losing the OO mental model, but gain very loose coupling (data coupling) and code that is easier to reason about. (The trade-off here is not for everyone though.)

On top of that, Clojure is an extremely flexible, interactive language, which is fantastic especially for GUI programming (as mentioned in the article).