The “internet” has been a platform for social networks for decades. The debate would center on whether this status has been ongoing for 20 or 30 years, not whether a connected network of humans, by way of machines, can be “social”. There was no web (WWW) at first, just the early forms of email, usenet/newsgroup activity and directories, followed quickly by instant messaging applications. The anti-social dimensions of the internet- those directories- were probably in the minority, in terms of activity.
Then we met the WWW, a somewhat impersonal highway of scrollable, corporate billboards. The anti-social internet assumption probably took form at this time. Once homepages arrived, anti-social shifted a bit to form the “Me, Me, Me” generation of applications and services. And the WWW began its slow transition to a social platform.
Now we have this social web structure. Pages that are really and truly just homepages with guestbooks, photos and various widgets. Funny how MySpace, Friendster or similar pages are really just pre-formatted GeoCities pages (or Tripod, or any other early homepages project). And the WWW is suddenly social, slowly catching up to the internet.