Take a look at this 40,000 word debate between Wikipedia editors about whether to capitalize the 'i' in the name Star Trek: i/Into Darkness.
For some perspective, my book was about 65,000 words.
This is such a great example of the causes of conflicts and why they can last indefinitely.
Some claim that these editors have too much time on their hands. That's clearly not the case. The number of Wikipedia editors has declined. The number of articles continues to rise. There is no shortage of work to be done.
So what happened here? We can break this into three components.
1) The initial conflict
Conflicts are caused by individual, team, project, organizational, or environmental characteristics. The spark here was project-based. Two people disagreed on a very minor problem.
However, discussion shifts to the rules of Wikipedia, Star Trek, JJ Abrams and standard editorial policy. It's no longer about the issue, it's about who best understands these issues. This leads to the second step of a conflict
2) Loss of status
I lied in the previous paragraph. It's not about who best understands the issues. The reason why people keep participating is because they don't want to be the person that understands the least about these.
People keep participating in a conflict because of the perceived loss of status if they cease participating - they lose right? The participants here don't care about the answer, they care about not losing. This is important for when you try to resolve a conflict.
Offline, people would quickly agree to disagree. However, online everything is visible to everyone and saved for posterity. We keep fighting to protect our own status in front of a perceived crowd.
On it's own, this is fixable by identifying ways to resolve the conflict without a perceived loss of status. This is usually via a compromise, a competition (polls/votes), or the two sides accommodating each other's viewpoints.
However, conflicts often bring in other people and lead to the 3rd stage of a conflict.
3) Group Polarization
When two people or two groups debate an issue, they don't persuade each other. When was the last time someone changed your mind online? When people/groups debate an issue they become more entrenched in their own viewpoint.
This is especially true with group debates. Defending the group's viewpoint is paramount in maintaining a strong group identity. This causes conflicts to continue indefinitely and spiral far beyond all reasonable length of debate.
At this stage, the groups are fundamentalists. They will only accept evidence that supports their viewpoints and challenge/ignore any evidence that doesn't.
The challenge in dealing with conflicts in your community is in either resolving the personal, team, project, organization, or environmental factors that triggered the debate, or remove the fear that leaving the conflict leads to a loss of status. Because by the time it gets to the polarization stage, it's too late.