This is freedom and it does enable creativity and can increase productivity indeed. But I've also seen it hurt maintainability as well: the original programmer moved on and now nobody can decipher their genius DSL.
Simple documentation for standard function definitions is fine but macros definitely need special attention. Some say macros are over-used but I think it's more of a case they're under-documented. Even if the name of the macro gives you a fair idea, documenting how it works and what is generates with examples goes a long way to deciphering them for maintenance. cheers.
Many people are like "I'll document it later" and it just almost never happens. Which is, as you said, a shame.