In response to The Speed of Gemini:
to reply you really need both to care and to put some serious rational thought into it. Well, technically you don't need to, but the culture of Gemini is more longform and so it just kind of comes naturally.
A counterexample would be usenet. I loved usenet, but plenty of very uncivil discourse happened there, to put it mildly. Back in the day, usenet didn't necessarily propagate in real-time either. A lot of it went over store-and-forward UUCP, so a post could take hours or days to reach somebody.
Fidonet tended to have more mature and civil discourse, as did PODnet, a Pagan-oriented BBS network where I spent some time in the mid 90s. These networks also had rules. Fidonet, specifically, was sort of straight-laced, a bit like ham radio. Even so, I saw my share of heated arguments on fidonet, complete with all of the forms of childishness of which we humans are capable.
My point? Long-form discussion doesn't by itself encourage civil discourse. It helps, because you can explore a topic in greater depth and tease out all of the little nuances that can't be conveyed in 140 characters. It also has to be paired with a culture, and Gemini -- at least for now -- has a really nice culture of early adopters.