I understand where you're coming from and agree to a large extent, but I think your hypothetical person's characterization of infix as a "basic capability" is a bit off. It's antithetical to Lisp's design to make use of infix notation. As far as Forth goes, I would say the same thing.
Agreed. Straightforward arithmetic is the capability, in Lisps represented in such a way as to fit with the philosophy of the language.
It's not like the majority* of languages see infix (or prefix, postfix, postcircumfix, etc.) notation as a basic enough concept to allow defined functions to make use of it. Arithmetic always seems to be the special case. No operator overloading, but arithmetic is pre-overloaded. Parentheses of function calls are all you need to keep track of subexpressions, but arithmetic will have an arbitrary and large list of precedences.
*correct me if I'm wrong. I know a fair few languages but mostly deep dives into particular niches. That could bias me.
