Your opinion is about an idea of Lisp that's simply not true. Both Common Lisp and Scheme are pervasively mutable and imperative constructs occur just as often

Your opinion is about an idea of Lisp that's simply not true. Both Common Lisp and Scheme are pervasively mutable and imperative constructs occur just as often as in "Algol." Clojure diverges from this with its nice immutable data structures, but that's a rather novel and distinguishing feature, not a core trait of "Lisp." I'm curious about where the idea originated that Lisp is an especially non-mutating language. Some of it is just that it's a garbage collected language with first class functions, so it's easy to classify it as "functional" which has associations to "pure functional." But Lisp is very far from a pure functional language. It's more like a general multi-paradigm language—like Perl and Ruby.