There's no use in starting a discussion if your mind is already made up.

This is very true. It needs to be about maintaining an open mind. Though in my case, I think there are times I take this to an extreme where it looks like I'm completely waffling between two decisions because of good points brought up on both sides. I suppose in this case it's best to step back and look deeper at each point and rank them (I'm now talking to myself as I'm writing this now).

And the 'destroy' polarization. Yup... I think it's more because they know people don't like to take the time to break things down, and would rather pick a winner. That just becomes a popularity contest, which may not be the best outcome...