Everything is moderated to the extent that you can choose to remove yourself from the situation. Moderation in some form has to exist to limit the chaos. It's not black and white either, sure anyone of a certain level of popularity will get trolls to some extent, you are right. That happens in real life too. I'm just saying that it matters 'where' the discourse is taking place and it matters who is involved. If you and I where having this conversation on Reddit, somebody would probably have trolled us already.
Are there really places on the internet you can "go to have health, civil debates" that are a) troll-free, and b) unmoderated? The world has neighborhoods, each one tnds to have its own police force.