> - mixing circles -- people are often isolating their friend groups into niches (pickelball friends, church friends, D&D friends...)

I was raised in a social environment where mixing circles was normal and it took me a while to realize that that's not how Americans do things. It certainly creates a lot of difficulties connecting with others, and at least for myself I am a lot less motivated to get to know people better when I'm the X or Y buddy they reach out to when the people they actually want to hang out with are unavailable.