Social Networks Eroding Forums?

Forrester's new Social Technographics Profile report hit the interwebs a few weeks back. (I'm catching up on my Safari tabs, can you tell?)

A couple of key points in the accompanying blog post:

As for Critics, those who react to content, this group hasn't grown at all. Looking deeper into the data, this is a result of a small but actual decrease in the number of people contributing to discussion forums. Why? Probably because much of this activity has been sucked into social network sites like Facebook.
I'm quite surprised by that - social networks largely offer discussion between people who already know each other, while forums allow the building of new discussion communities. Perhaps our understanding of forums is imperfect?

The explosion in Joiners from 35% to 51% of online Americans reflects the appeal of Facebook, as both press coverage and invitations from friends suck more of us into social networks. Meanwhile, Spectators -- those consuming social content -- reached all the way to 73% of online Americans, which should end any remaining skepticism about whether this social thing is real.
Social is becoming the default way of viewing the web.