The HN crowd tends to be dismissive of social media (a lot of "get off my lawn types" around here), but I came from the world of BBSes, and to me social media is simply an evolution of what BBSes were. For years I tried to figure out how to reproduce the sense of community that BBSes brought about, but never found the right niche. Then I realized Facebook was actually a evolved version of a BBS.
I am friends on social media with complex people (who understand nuance) who tend to use social media carefully. They use it to share events, describe experiences (in pictures and words), and once in a while write insightful status messages. They usually don't have extreme views, and tend to debate issues in an even-handed way. I find being on social media with these folks to be enriching because I get to learn a thing or two.
If you follow the right folks on Twitter, you'll get to overhear a lot of conversations about the important issues in Python, R, or what have you, and gain a context that eludes most people who learn programming languages from books. Social media is good for that.
Less complex people tend to share on whatever they found on Reddit, their favorite political website or whatever trashy site that supports their preconceived notions. They tend not to write a lot of prose, and when they do it's not very well-thought out. Many of our older less tech-savvy relatives tend to fall into this category. We tolerate these people because we're related to them, but they are the ones who use social media in a somewhat unhelpful fashion. And before social media they found entertainment in forwarding fake news emails without verifying them on Snopes. But we mostly dismiss them because their believability factor is low anyway.
In the middle are the really dangerous folks, the really intelligent but extremely partisan folks. I won't name names, but if you follow certain celebrities in the AI world, they will often share partisan and unexamined articles that reveal their political bias. You would think the more intelligent someone is, the more of a critical thinker they would be, but it turns out that most people who are good at one thing aren't usually good at everything.