What was it exactly that got r/cth banned from reddit?

The head of reddit's censorship team is literally a CIA alumni. An extremely active leftist sub that wasn't self-defeatingly sectarian or a captured radlib tendency like the vshites, and that terminally online enough to be shaping discourse in general wasn't something they could tolerate it.

What ultimately did us in was the nonce admins (spez et al.), their decision to ban /r/The_Donald, and the belief that they had to make a burnt offering of an infamous leftist sub as well, or else the site’s humors would become imbalanced, or something. At the time CTH had developed a reputation for such controversial takes as “kill slave owners,” jokes about assassinating elected officials (which were bowdlerized as “baseball” jokes, to no effect since they picked up on what “baseball” meant), saying “kill cops,” and (I think) brigading other subs?

We were warned a few days before Armageddon. And then the rest is history.

Advocating for the death of slave owners wrt John Brown, but it was tit-for-tat for /thedonald