It's not about the language, it's about how you approach the problem. Maybe their rationale is that using C discourages the use of built-in constructs or libs t

It's not about the language, it's about how you approach the problem. Maybe their rationale is that using C discourages the use of built-in constructs or libs that circumvent doing the real work. For this type of problem, it also hints at your understanding of indirection and pointers as opposed to stack allocated values, etc. Pretty much a pre-requisite if you're doing anything remotely performance-critical, like rethinkdb is. When you're dealing with a higher level language, that's all abstracted away by references.