For example, if synchronous message passing would be used exclusively, large, distributed systems generally would not perform well enough to be usable.
en.wikipedia.org Over time, the operating system gained a hierarchical file system, preemptive multitasking, support for multiple users with access controls (although no memory protection), lightweight threads, message passing primitives and pipes.
en.wikipedia.org With a front-end processor, it has a distributed memory and message passing system.
en.wikipedia.org Asynchronous message passing, by contrast, can result in a response arriving a significant time after the request message was sent.
en.wikipedia.org Note that with this type of message passing it is not a requirement that either the sender or receiver are implemented using object-oriented programming.
en.wikipedia.org