[PeterisP]

The goal of a public debate is to influence the perception of the many passive listeners, not the few other participants of the debate; There is extensive flow of information/communication, but it's simply not aimed towards the other participants of the debate.

So a key part of such debates becomes influencing or provoking others to talk about things that advance your cause and avoiding discussion of things that hurt it. E.g. if someone says "you eat babies" and you respond with extensive evidence that you don't, then that public debate becomes a debate about you being a baby-eater and not whatever you wanted to promote.