I’m not sure about “not valid in most cases”. Controlling memory matters in many kinds of real-world applications. And I’m really excited about some work we’re doing for making it easier in OCaml. This talk fro Stephen Dolan is an exciting preview of that work.
I very much prefer Lisp as a language over C++, but being able to represent data in a more compact way for performance when needed doesn’t sound like a bad idea to me! I’m purely speaking without any language design / implementation experience