Functional Programming - Lots of emphasis on recursion, why?

Pure functional programming means programming without side effects. Which means, if you write a loop for instance, the body of your loop can't produce side effects. Thus, if you want your loop to do something, it has to reuse the result of the previous iteration and produce something for the next iteration. Thus, the body of your loop is a function, taking as parameter the result of previous execution and calling itself for the next iteration with its own result. This does not have a huge advantage over directly writing a recursive function for the loop.

A program which doesn't do something trivial will have to iterate over something at some point. For functional programming this means the program has to use recursive functions.

Church Turing thesis highlights the equivalence between different computability models.

Using recursion we don't need a mutable state while solving some problem, and this make possible to specify a semantic in simpler terms. Thus solutions can be simpler, in a formal sense.

I think that Prolog shows better than functional languages the effectiveness of recursion (it doesn't have iteration), and the practical limits we encounter when using it.