There are many points to debate.
Premises, which may be based on supposition or logic rather than a simple "fact"; or may be rejected by the other party for a number of reasons, including interpretation or error. Careful definition of terms helps here.
Argument, which may be based on specific context or circumstance, or influenced by begged questions or subconscious bias. Strict adherence to boolean type logic will help here.
Conclusions, which may not be supported or may take a leap of faith. It can be very hard to get people to see the assumptions they make.
The only pure debates where there can be no disagreement is in the highly controlled language of mathematics - some of those arguments may be terribly complex and misleading, but there alone will you find concusive proof in the end. When you're dealing with the political or religious debates often found here, there is a great divide in value systems which are never willingly examined, let alone released.
For much of debate, there can always be multiple positions because there is very often an element of personal judgment to be made. Some judgments seem to make more sense than others, but are still based on a point of view that is not an objective universal truism.
But then, there is very little structured debate here, as well. And too often opinion is vaunted as fact.
"People dont agree to disagree, they just get tired of arguing"
That may be true in some cases. I don't think you'll find me doing that. But I often refuse to engage further when it's clear the other party is intentionally ignoring what I've presented.