I think the causal relationship is not quite that way.
better connectivity -> destroyed physical limits on group size -> groups not only get larger but also more ideologically homogenous because they're moderated by a central authority like how physical crowds are moderated -> people make friends more easily in those homogenous groups OR get kicked and start their own group, which also has the potential to get larger and more homogenous without limit -> groups have larger differences and clash harder
better connectivity -> destroyed physical limits on group size -> groups not only get larger but also more ideologically homogenous because they're moderated by a central authority like how physical crowds are moderated -> people make friends more easily in those homogenous groups OR get kicked and start their own group, which also has the potential to get larger and more homogenous without limit -> groups have larger differences and clash harder
More friends is a symptom rather than a cause.