That's not a bad idea, but I foresee two problems. 1) Sometimes you don't foresee a debate when you post a thread in the first place. If a debate occurs, the thread (or part of it) would have to be moved to the debate section. You'd end up with most of the thread missing in the original, and when it's moved, it would pick up in an odd place. 2) There really should not be any serious debates. They tend to get out of hand and a debate section would be an open field for things to get out of control. That would not be permitted even if there were a special section. I'd imagine that those threads would also end up locked.
People can express their opinions, no problem. But when they keep forcing that opinion again and again in the same thread, and it gets pushy and disrespectful, it's time to end it. Sometimes there is no right or wrong and it's a matter of personal belief. You cannot or should not ever force someone to believe what you do. If you want to state a fact, state it, back it up, and back off.