I have a sneaking suspicion that this is how the majority of productive political discussions happen - around the edges of other things.

People who show up for political debate generally do so with knives drawn; you hear from the loudest people with the most solidified views, and the stuff that rises to the top is playing to the crowd instead of engaging in extended discussions. But in a rec sports team, a movie club, or a tech forum, people aren't grouped by viewpoint and vitriolic arguments are a distraction from the original cause. So those places seem to breed conversations where people take the time to hear one another and avoid breaking down into pure tribalism.