Your example of device files is hardly universal, and the way it works is useful.
It literally doesn't make any sense whatsoever for many of these devices to behave like physical files, e.g. be deletable or whatnot. Yes there is an exception to every nonsense like this, so yes, some devices do make sense as files, but you completely miss the point when you ignore the widespread nonsense and justify it with the exceptions.
"Everything is a file" is about reducing most operations to 4 very abstract operations--open, read, write, and close. The latter three take handles, and it's only the former that takes a path. But you're conflating the details of the underlying filesystem implementation with the relevant abstraction--being a file implies that it's part of an easily addressable, hierarchical namespace. Being a file doesn't imply it needs to be deletable. unlink/remove is not part of the core abstraction. But they are hints that the abstraction is a little more leaky than people let on. Instantiating and destroying the addressable character of a file poses difficult questions regarding what the proper semantics should be, though historically they're deletable simply because using major/minor device nodes sitting atop the regular persistent storage filesystem was the simplest and most obvious implementation at the time.
