oiu isn't unix
To paraphrase Douglas Comer, if you want Unix you know where to find it.
In the '60s MIT, General Electric, and Bell Labs explored the state of the art in time-sharing operating systems in the form of Multics. Shortly thereafter Thompson and Ritchie took the best ideas and ran with them, giving us Unix. A Multics user from the '60s would not be at all lost if sat in front of a RedHat Linux prompt with a cue-card listing relevant shell commands. In fact, most of the features of Multics, left out of Unix for simplicity and expediency's sake by Ken and Dennis, have found their way back in after being reimplemented in that universal assembly language, C.
oiu also is not the MacOS, nor is it Windows
(Although the MacOS and Windows both seem to be reinventing Unix.) In 1984 the Macintosh introduced to the public a new model for human-computer interaction. Direct manipulation with a modeless, visible interface proved to be a friendlier and more attractive environment to work in than the command line although many still argue that the command prompt provides greater flexiblity for scripting and for chaining simple tools in powerful aggregate ways. Unix with X Windows of course lets you have as many command line windows as you can handle.
There have been advances in system design since 1969 and even since 1984
KeyKOS used a transactional persistent-memory system with a novel security architecture. Synthesis showed the advantages of run-time kernel code generation with self-traversing data structures and non-blocking synchronization methods. The Apple Newton implemented a processor-neutral virtual machine. The Xerox Star had objects all the way down, and any part of the system could be modified by the user by editing the on-line high-level-language source code. Oberon Slim Binaries illustrated that load-time compilation can replace linking, giving a net increase in load and execution speed while at the same time providing processor architecture independence. Distributed Shared Memory systems provide a parallel computation model equivalent in power to message-passing systems. Kansas shows the usefullness of a shared visual workspace across physically disparate locations. In Oberon and 8 1/2 everything visible on the screen can be selected and used as a command or a parameter, blending the ease of use and visibility of the GUI with the power of the command line. The Self project investigated run-time code optimization in an agressively simple dynamic language. Beowulf systems aggregate the computational power of inexpensive machines. Recursive virtual machines isolate un-trusted processes and Plan 9 demonstrates the power of union directories. Some people even claim to have figured out process migration.
oiu is unix only in the degree to which it attempts to take the best of these new ideas and run with them