Sort of - consider when Lisp originated. The heritage/age comes from a time before the research in persistent data structures happened, or even the issues with mutability were fully known. Because of that, idiomatic Lisp tends to be mutable, and no one is writing a new Lisp who isn't already familiar with another one. That's not to say immutability isn't worthwhile there, or that no Lisp standard libraries support it, but mutability tends to be the default assumption from what I've seen.