IMO, the problem has nothing to do with the internet. Instead, the problem has more to do with poorly controlling marketing and homelessness. Political correctness also takes a toll.
When I lived in the Bay Area, most of the time I was randomly approached, "on the street," it was from a homeless person. Thus, I was less likely to be friendly to someone when I was in areas with high amounts of homeless people. If the Bay Area took care of the homeless situation better, there would be less people approaching me, and then it would be easier to interact with strangers.
But then, what about being in stores, malls, ect? I then need to put up defenses against aggressive marketing. That also makes it hard to be friendly. If we considered unsolicited marketing as insulting, we wouldn't need to keep our defenses up in places of commerce.
Even political correctness takes a toll. If I start talking with someone who has a different opinion than me, or is a difference race than me, faux pas get blown out of proportion. No one wants to make friends with someone who's going to scream at them for being a bigot because they lean a little right, or be labeled a libtard because they lean a little left.