Interesting article, to me it just appears to be deciding how much you know at compile time vs runtime. (Runtime expressibility vs compile-time proofs) If you make your code a DSL you’re implicitly limiting your code to the semantics of your DSL, (you know at compile time that your code will do some finite set of things) while if you enable arbitrary code to be passed as higher order functions you lose this compile time knowledge. In the distributed systems case this is a positive because you want to limit the behavior of programs sent over the wire for security reasons.