It definitely gives people super-specific social niches in which to nurture their worst habits and views in a way that's not just unchallenged but even encourag

It definitely gives people super-specific social niches in which to nurture their worst habits and views in a way that's not just unchallenged but even encouraged. People who are chronically online tend to live in extremely insulated social bubbles. When you go out into the real world for your socialization time you tend to become less radicalized because you're more likely to encounter decent human beings with differing views from yours and your worldview becomes broader for it. Most online communities actively discourage giving others the benefit of the doubt and instead prefer dismissing community-consensus-defying views with either overly harsh labels or extreme skepticism ("explain why you're not a troll for disagreeing with me politely", basically). So in other words, I guess what I'm saying is that the internet seems to have given rise to a new wave of what are effectively cults. They encourage extreme views and extreme rejection of those with outside perspectives. Then when you conform to those views and behaviors, you tend to become socially isolated IRL, which leads to emotional dependence on the radical online community. It's a cycle of bullying that's extremely cult-like, and it's extremely common online.