The pre-internet world was much more of an "echo chamber" than today. The internet has created a constant firehose of exposure to diametrically-opposed beliefs, and this is what has actually driven "polarization." It's a self-defense response to constant exposure to conflicting worldviews. It was easier to find common ground before communication was this broad and instantaneous. You're more likely to have at least some things in common with those in close proximity, making compromise easier. (This isn't just me having an opinion, it's been studied and IMO the argument holds up.)
we see this as closely related to the kinds of urban/rural conflict that drive a lot of politics
it's
there are quite a lot of people who choose to live somewhere small and isolated because they do not want to be surrounded by vast quantities of people who are different from them
the internet makes it impossible NOT to be. it doesn't matter if you live in a cabin in the woods, social media is right there with you
we shouldn't be surprised that there's strong feelings about it