The topic was immutability, not Clojure?

But ok, if mutability is always worse, why not use a pure language then? No more cowardly swap! and transient data structures or sending messages back and forth like in Erlang.

But then you get to monads (otherwise you'd end up with Elm and I'd like to see Apple's payment backend written in Elm), monad transformers, arrows and the like and coincidentally that's when many Clojure programmers start whining about "jumping through unnecessary hoops" :D

Anyway, this was just a private observation I've reached after being an FP zealot for a decade, all is good, no need to convert me, Clojure is cool :)