A Pew Internet & American Life Project survey of early Internet adopters showed that the most common reason they got online was to connect with colleagues. Granted, they were social networking through BBS’s and mainframe shared time, but it was social nonetheless. (You other early adopters can probably cite the appropriate quote from The Breakfast Club. A fabulous prize will be awarded to the first to cite it in the comments of this post.)
The pre-2000 buzzword for people connecting online with each other was virtual community. This term was put out with the dot com bubble trash and is now covered under Web 2.0/social media/etc. What is different now is the greater scope of people connecting online and the greater diversity of easy-to-use tools for doing so (and lots of money being made by putting advertising on all of it). These are not insignificant changes but it is all rooted in a common desire of many internet users, then and now.
To paraphrase one of my favorite quotes, social networking is simply more evenly distributed these days.