Learning to think rationally precedes learning to have rational discussions.
Discussion basically uses two skills: thinking and dealing with other people.
Language is part of thinking well. It'd be useful even if you were stuck on a desert island alone for the rest of your life. You should have practice and success using language in your thinking before trying to use language in discussions.
Looking at many sides of an issue is part of thinking well. You should be doing that alone. So discussion shouldn't be a big change where things go from one-sided to two-sided (or more). Discussion should involve people doing the many-sided thinking they would have done alone.