Scale isn't the point. It's the nature of event based systems. Why do we have interrupts? Having an abstraction there makes developing operating systems easier. Why do we have hooks in git? Because we want to add or remove software integrations at run time, without touching git itself. Queue based systems have similar characteristics as event based systems.

It's not a bad idea at all, you probably use message based systems every day without thinking about it, culturally however the idea is irresistible for enterprise developers who live for abstractions. Just something to keep in mind.