> It is possible to write complex and performant programs without allocating memory.

I assume you mean by only allocating on the stack? Those are still allocations. It's just someone else doing it for you.

> And in some languages, where you only operate on values, and never worry about where something is stored, allocation is just an implementation detail.

Again, that's someone else deciding what to allocate where and how to handle the pointers etc. Don't get me wrong, I very much appreciate FP, as long as I do information processing, but alot of programming doesn't deal in abstract values but in actual memory, for example functional programming language compilers.