The operation system already very much behaves like an object-oriented system, even in a languages without language support for this: you ask the OS for a handle, which has to be passed as the first argument to any system call. The kernel has figure out what object the handle refers to and redirect the call to the appropriate subsystem. This is abstraction and polymorphism. And of course, the kernel won't give you any access to internals by default, which gives you encapsulation.

The argument of GP is that file-oriented interfaces like `rewind` or `seek` are ill-suited for anything that doesn't behave like a seekable file. `read` and `write` work well for anything with a streaming interface, but are utterly unsuitable for things like processes. You'd have to layer protocols on top of it.