I think this relates alot to what other posters are saying about how it's difficult to break into established social circles without somebody introducing you in

I think this relates alot to what other posters are saying about how it's difficult to break into established social circles without somebody introducing you in. After all, you're more likely to make friends with a room of individuals than a room of cliques. What social media does is it greatly strengthens preexisting social circles that there is less incentive for someone to be open-minded and make new friends. Take video games for example, I can personally attest people were alot more sociable and open to friend requests a decade ago than today. One perception on what is causing this would be Discord. In the past, most people playing would be individuals, and group activities would naturally force people to socialize with strangers. The friends you made in one game would not follow you to another. With Discord, nowadays it's more of alot of premade groups of friends playing these games, so there's no reason to socialize in public chat or care about strangers. Now Discord isn't new, Skype or BBS existed years before, but they were harder to set up, so pre-made groups were less prevalent and the barriers of entry would naturally mean people with more of an open mindset would be using them. Discord in contrast is very easy to get started with, so the more "conservative" elements would take precedence.