I find that debate actually teaches people to get into better discussions, and that those who don't have this experience have to rely solely on personality traits which are rarely there. For example something you might try is to make small errors here and there for which addressing the error would be a distraction or a poor allocation of mutual attention.

A good debater keeps their focus on the outcomes they want and will not waste attention or time on distractions. But watch how many people cannot help but waste their working memory and attention on garbage, like an automaton that must run line by line or attack dog that must bark at every single thing. Consequently this isn't actually a good filter because too many high quality people will get trapped by this.