I think you're conflating "chaining function calls together" (aka "threading function calls") with unix pipelines, which are all about running separate programs

I think you're conflating "chaining function calls together" (aka "threading function calls") with unix pipelines, which are all about running separate programs in parallel & connecting their io streams together (with the kernel regulating the flow of data between them). Threading functions together is basically about being able to write read -> eval -> print -> loop rather than: (loop (print (eval (read))))