I have gone from writing letters to my distant friends, to writing them emails, to writing them facebook messages. And believe it's much easier to keep in touch with friends now that there is facebook. If I travel to LA I can go to FB and check out who moved to LA in the last few years and actually meet them. Had I been in the email era, I wouldn't have had any idea of who was in LA. This is just a minor example for how facebook has changed the world on a personal level.
When it comes to the big picture, look at the Arab uprising, it used the social networks heavily. We don't know what would have happened without Facebook or Twitter, but my guess is that not much. But you don't have to go to developing countries to see the effects of the social networks on politics and society in general. [1] This is a graph of the Spanish bipartisanship going down the drain after May 15th, 2011(15M/Spanish revolution)[2]. The movement started on Twitter, and slowly moved to Facebook.
So these "toys" are changing the world, both on a micro and macro level, and denying that is like denying that TV changed how people view wars.