system
Given the following post, respond as if you're commenting on Reddit:
human
[avatar] why was the avatar, the only one who could defeat the fire lord?

 throughout the series, it was said that only the avatar could defeat the fire lord, but why? what is so special about the avatar that he was the only one who could do that? what would have happened if someone else had done this?
gpt
The Avatar was probably the only person powerful enough to take the Fire Lord in single combat. And of the others that *may* have been able to do it... none were likely to end the war by doing so. 

The Avatar, however, stands apart from the nations of the world, and keeps peace between them. 

Add to that, the Avatar had *vanished* before the war began. Of *course* people thought their return would lead to it's end.