I knew plenty of non-leftist political posters when I was on Facebook. Many were fine and I had no problem with them, but some were people I no longer recognized, trapped in their own perverse info-bubble. And yes, there were one or two on the left side of the spectrum who fit this description, too, and I lost respect for them as well.
It was sad to see people who I knew were intelligent and decent in many respects get confined into the space of their ideological tribe, but I began to realize that Facebook in particular seems to profit off of this kind of madness. Rage posting
was their business model. They figured out that people are addicted to the train wreck, either as participants or as merely passive observers who want to be somehow entertained. I mean, to a great extent, I think we can certainly see that dynamic play out here. I admit that I'm no better in this respect - I fall prey to these impulses to lash out as well. And yeah, I know, it's stupid. Whether we like it or not, I guess we do take our politics personally - probably a lot more personally than we should in some cases, though in other cases it's hard not to take it as a personal affront.
Tl/dr, that's why I deleted my FB account. Instead of experiencing the thrill and delight of reconnecting with relatives who lived far away and with people whom I had fond memories of and hadn't seen in years, that delight devolved into toxic cynicism as I saw people reveal their worst prejudices and irrational fears. In the end, I was left with a sense of great despair that our society was and is now tearing itself apart, for trivial reasons in many cases. Adding insult to injury was knowing that there are people in Menlo Park, California who are getting paid a shit ton of money to do this, to goad us into rhetorically disemboweling each other. So much for Mark Zuckerberg's brining the world together crap. Quite the opposite: I saw relationships die in that space.