For a number of years, I've heard complaints about the internet, that it promotes social alienation and shortened attention spans. It strikes me that these are the same complaints about TV that we heard for 50 years.
I don't think we can really blame the Internet or TV for the dumbing-down and brutalization of our culture. Our culture is becoming brutalized because appealing to our inner Neanderthal is enormously profitable. A lot of money can be made by pandering to our basest instincts from lust to revenge. Sex and Death, especially in combination, have always been sure-fire crowd pleasers since the Paleolithic era. Spectacles of sex, violence, and glamor are even more certain money makers than striking oil.
Politicians and corporate autocrats have every interest in keeping our attention focused on that bright shiny new thing over there (so we won't notice what they are doing over here). It helps that we are easily bored and always demanding bright shiny new things. The Internet and TV are means to ends, they are not causes. Responsibility lies not with the technology, but with the humans using it. Hammers deserve no credit for building the Taj Mahal, and no blame for killing people.
My generation disses the current younger generations (just like the previous generations dissed us) for being shallow and self-absorbed; as if we were all listening to Mozart and joining the Peace Corps. As I recall, we were all getting wasted and listening to Led Zepplin. If we had back then the games and toys that kids have today, would we really have played with them? Hell yes!
The social alienation and brutalization were there before the technology, and would still be there if we got rid of our gadgets. Alienation and brutality are there because someone somewhere makes a lot of money off of them, and because we want to be left alone to enjoy our little fantasies of power and revenge (since we really don't have much power and those who have a lot of power will never be held accountable).