This is not a new question I have been hearing this for years but not from someone like him, a historian.
I see the internet as two things. The greatest repository of knowledge ever assembled. Storage of books, magazines, newspapers. The world of info is at your fingertips.
Sadly the storage has been corrupted with bad info some that depositors sincerely believe is true and some depositors upload deliberate lies. Elections can turn on the deliberate lies.
The second part is social media. We see discourse being used by a president stirring hatred. Although this is not new leaders have used speeches to divide or unite, they have used film then radio and tv. The internet has in some ways a wider reach and unlike tv and radio if you missed those broadcasts you were pretty much out of luck.
Yet social media gives everyone a voice. One voice does little but the ideas quickly get reinforced by others.. The most insidious ideas once were seen by at most a few thousands now the writers get on tv. Breitbart is perfect example. I doubt if in as late as the 80s it would have been any more then a news letter with a small clique audience.
Just look at immigration the most strident bigots are listened to. Look at the wall, just 10 years ago it was dismissed as an unrealistic dream by bigots. Even republicans like George W Bush wanted comprehensive immigration reform. Now due mainly to internet the wall fanatics control the issue.
Social media thanks to anonimity has allowed bigotry back in. People won’t say aloud what they say online. Although this used to be more true then today. Now that line is just about dead.
I agree more with Burns then disagree. Although he will be literally true if a tweet sends us into WW3.