The cost of communication, price and latency, has always defined the structure of our communities. Letters, cars, phones, internet, every invention expanded the reach of individual "community" while cost acted as friction to prevent bad ideas from gaining too much momentum - individuals still had to engage with their local community too.
Social media finally brought the cost to essentially zero. We can talk to anyone or about anything at any time. Great for early adopters and their critical/creative tendencies, but mass adoption by consumers has enabled mass tribalist tendencies to fully decouple from proximity constraints. This might be the "boiling point" for historical conflicts, but "supercritical" seems more appropriate here.
Media consolidation has been synonymous with consolidation of broadcasting viewer opinions and their political parties - many unhappy with both choices but faced with the false dichotomy of "their guy" and "the enemy". Meanwhile grass-roots are numerous but now diffuse and ineffective, cut off from broadcasting influence and digitally disconnected.
Hopefully society starts correcting back to offline engagement. Anecdotes suggest we are, but undoing the damage will still take a while.