Is the lack of cons cells a significant limitation?

Limitation is the wrong way to think about things when computational equivalence is in play. It's about mental foundation. Lisp at its core is like driving a Turing machine, Clojure is not.

I would call these different dialects of Lisp. The data doesn’t have to be a function. It’s illustrative. The patterns of application still work. What’s the difference if delimiters are different or if you are calling JVM libraries? The high-level ideas are still right there. Consider JavaScript. It is definitely not a Lisp, but if you model it as Lisp in C’s clothes, then all of a sudden IIFEs make total sense. The point is that it’s a helpful mental model for languages other than Lisp.