> I got the sense that people became more anxious about what reached that "good enough" mark

Bo Burnham has some interesting comments in his "Inside" special about how social media makes us disassociate from ourselves and think about both living in the moment and how it will be perceived afterwards. I think that's a big part of what causes this - after you know that you're not just posting for fun then you have to think about why you're posting something and what it means. This has caused by to basically stop using them because it never seems "worth it" to post something