The essential equivalence between I/O and IPC has been recognized by many and is perhaps obvious to most. Nevertheless, a great many different sets of IPC-only primitives have appeared and continue to appear. Furthermore, operating system designers tend to extend existing operating sytems by adding IPC-only system calls, rather than by means of generalizing the I/O-only system calls.
Given the pletora of different and not-so-different sets of IPC primitives, and the relative consensus on I/O primitives, the prevailing approach is probably not the best one.
Prof Herman Venter