If debates are about convincing a audience that a specific viewpoint is correct, or at least the opposing is false or had serious doubts, then facts are indeed irrelevant.

It is merely about who is more convincing. Every lawyer knows this by heart.

If debates are about convincing your opponent that you are right, then it depends on your opponent. People like Ez rider and Arch refuse to accept anything they do not like. Mountains of facts are completely irrelevant in such a debate. To convince them would require either mind control or a act of God. For reasonable people, facts are important as they produce a foundation for which compelling arguments can be made. More importantly, it is how one presents such facts more then what facts they actually use. One could use every fact in the book but present a front so hostile that no one listens. They're right, but they have failed.

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"You are, of course, free to make your own calls on how much rationality you want to impose upon yourself." - Kronus