And Google Docs is X% there as a MS Office replacement.

Does Office have robust real-time simultaneous editing. I imagine Office 365 might have (does it?) - but how about desktop Office?

Genuine question. I'm asking about Word, Excel and Powerpoint.

I used the Office collaboration features last with Office 2013 on Windows, and they were quite primitive. Basically, the document is synced with OneDrive.

The online version of Office has realtime collaboration AFAIK.