We want to put our focus on two particular points of view, so we want to limit the debate to two participants, namely the debaters. At the same time, we want to represent as much of a point of view as we possibly can, so we want to have as many participants as possible. This is where supporters come in.
Supporters sign up to help out a debater they tend to agree with in a given debate. They don't even have to agree exactly. Their job is to respond to posts made by anybody in the debate with information that the debater they're supporting could use, or suggestions on how to respond.
Supporters can also support mediators in a debate, if they feel particularly interested in or qualifid to give suggestions on how to guide the discussion.
