There’s only so much time in the day so we can’t talk about everything.  Given the opportunity cost, ideas that are obviously bad aren’t worth talking about, even if you are someone who always considers both sides of every issue.  This means that if you discuss an idea you demonstrate that you don’t think it’s obviously bad, even if what you conclude from your discussion is that the idea is obviously bad.

Now if I think that an idea is obviously bad and I hear a friend, or politician, or media outlet engage in a discussion of both sides of that issue, I conclude that they have the wrong priorities, even if they ultimately agree with me on the idea.  Therefore, my friends, politicians who want my vote, and media who want me to listen to them will not even bring up ideas that I think are obviously bad.  Even if I am wrong.