Hi John,
The wording you quote is mine  the article as I found it back in July 2006 did indeed only talk about  open systems as an interoperability phenomenon, with the exception of one line:
 It can also be defined as a system that allows access by other systems, hence 'open' system.
So the article really wasn't talking about social synergy even before then  but I changed the wording precisely because I thought that aspect, although not in the scope of this article (in my opinion), was still worth discussing.  (What I had been thinking about when I did my edit was the MIT AI Lab systems that were available for open access via the ARPANET back in the late '70s / early '80s.)
I think it would be great if you could create an article to discuss the social aspect, maybe using your article as the foundation for it, and it could be linked to from this article and others.  But I still do think it's a different topic from open systems as covered on this page.