I also found that my mental health and general experience of life improved significantly when I got off of Twitter and Facebook (and this was years before 2016—thank god I wasn't there for that). Social media never really elicited in me the "My life pales in comparison to everyone else's lives" insecurities that many commentaries about the ills of social media have pointed to, but I definitely did feel like no matter how much time I spent I could never keep up with engagement requirements. Paradoxically, and despite commentaries that "you can't leave social media without becoming isolated", doing so has made me feel more social engaged, because the people who are willing to contact me via means other than a tweet or FB invite have generally been more genuinely invested in having a social relationship with me. Dreamwidth, by contrast, is much more to my pace: there's no expectation that a response is required within minutes or hours, or even days, in many cases.

my impression is that most people using social media treat the contents of any individual tweet/post as something that exists in complete isolation from any broader context.
I've noticed this too and it fascinates me because it exists alongside the contradictory tendency to dogpile and permanently ostracize users for the content of a single post. Not that I always disagree with this: James Gunn, for instance, absolutely deserved to suffer consequences for those posts, no matter how long ago and "how different things were" when he made them. But that's not always the case, and you can't really predict which way the social media undercurrents will flow in any given instance—another reason I prefer to stay clear of it entirely.