I mean, "more comfortable to just retreat to a place with common similar beliefs" is a good theory. But it is hardly the only one I can think of. Off the top of my head I also have:
1) Wealth is being eroded by the response to the '08 crisis leaving known-bad cultures to thrive in the lending industry. Social fabric starts to unravel due to lack of wealth creation.
2) Academics have had a long history of being in tension with democratic ideals. Famously, right when they came up with the idea of 'academies' Socrates was executed by a jury trial. More recently, communism had strong support in academic circles of Europe. We've massively increased the exposure of people to the university culture in the last 1-2 generations. Maybe technocrat leanings are leaking out? Technocrats don't compromise well on social issues, they believe there is a best answer.
Basically, the problem might not be algorithms and search bubbles, even though this is a forum that knows a lot about algorithms and search bubbles.
