That is retconning "social web" to cover every kind of interaction. Applied hindsight-bias. Before the web, there were boards on services like CompuServe, The Source, AOL, and others, that simply had names that you told other people. It's not a new technology to email someone you're going to the mall when before email you would just tell them over the phone or whatever.
The point isn't that people were being social over email. The point is that people were using email as a social layer on top of the web (i.e., they'd email links around). What we now call the "social web" is just the web as a platform taking over functions that before were performed over other internet technologies like email and IM.
http://en.wikipedia.org/wiki/Retroactive_continuity