… is that you don't need language support for recursion to implement recursive data structures or recursive functions on data structures
I haven't written a blog post on this (yet), but if you're curious to learn more you can check out how this is done in Dhall (a language that doesn't support recursion):
The post that I personally learned this from was Wadler's Recursive types for free!, although that's a bit more of an advanced introduction.
A related post of mine along these lines is this one:
… since the way you model recursion in a non-recursive language is to encode it as a fold.