We can't strengthen our ideas if we only talk to people who agree with us.
Simplistic? Possibly. But when was the last time you - as a mentor or mentoree - sought out a dissenting opinion? When did debate become a bad thing? Why is it necessary to dismiss the feedback of all nay-sayers?
Scientific theory thrives on attempting to disprove itself, not prove. (I won't attempt to explain Popper's theory but I recommend reading about it)
"Winning" the debate should not be about everyone agreeing or anyone being silenced. Marriage was defined for years as between a man and a woman and debate has brought us to a new(er) definition. Not all agree. Opinions are still forming in all areas, including mainstream. It was debate that was part of bringing about change.
Ideas are about change. Debate creates views into that change so we can manage the necessary adjustments with some foresight and perspective on the opinions helping/hindering transformation.
Welcome debate. Listen to be heard even more strongly!