It's amazing. It's something I've noticed time and time again in online communities. The more you restrict people's speech, and the more you force people to be civil and kind to each other, the nastier and more immature people get. It's almost as if, if you treat people like children who can't control themselves without jannie intervention, they will take on that role and act on it, whereas if you treat people like adults who are responsible for their own actions and for their own reputations, they'll act like adults instead.
We don't all agree when it comes to policies and worldviews, yet this whole place is incredibly welcoming, regardless of how much more left-leaning we (and especially half-KIA) are compared to our neighbours.
This sort of neighbourly and genuinely positive (and not just "cashier smile" kind of positive) interaction between people, especially people who don't necessarily fully agree, is what is going to lead to the healing and rebuilding of western society after all these calamitous events. It takes all kinds of people to keep a society running, after all.
I tried googling but really couldn't find anything I'm sure about. What's SSC and what happened to it? I found a sub called Slate Star Codex but I have no idea what that is.
From my limited understanding:
SSC is SlateStarCodex. Run by a center-left dude who posted overly long treatises about random topics, frequently intersecting with politics. He often acknowledged certain realities about how the left vehemently attacks differences of opinion.
I remember one blog post he made where he outlined and acknowledged the truth of "if an organization is not explicitly right-wing, it will eventually be taken over and become left-wing".
Slate Star Codex is/was a blog, though that description doesn't do it justice.
If you follow the link you'll find a much better description of what happened to it than I could provide.
/r/slatestarcodex (and r/TheMotte) are both subs centered around the SSC community.