Modern discourse is clearly affected by the "leveling" of communication that a popular internet provides. People frequently interact with very large conglomerations of people, rather than primarily with their geographic neighbors. This analysis suggests to me an explanation for why massive internet inter-communication can be a bad thing for discourse.

And this matches intuition in the real world for different reasons - friend groups formed mostly by environmental and proximal circumstance result in more diverse yet still tightly-knitted communities than, say, a niche hobbyist subreddit might. So you have the opportunity to be exposed to new ideas by trusted members of your in-group.