I think the important thing is to be aware that there are several different types of debates or discussions with different purpose. School debate teams focus on combative debates - debates where the goal is to convince an audience, not the other side. The type politicians tends to engage in during campaigns.

But it'd be good if people got better training in "cooperative" debates, where the purpose is to learn and listen. I can't recall many instances where that was encouraged in school, but there were a few. All of them were focused on a subject, though, rather than actually teaching the skill of listening and debating constructively.

There's a space for both - sometimes you need to be combative -, but people switch to combative mode way too readily.

To your point on the time formulating a response: Online I find a good measure of whether I'm "listening" or gearing up to being combative is whether I end up significantly re-writing my reply while writing it as I process the comment I'm replying to, or if have it "ready and loaded" to fire back at someone by the time I hit the reply button.