On a small forum, you can do things rather leisurely. But that's plain impossible on this scale. If you truly want unrestricted arguing, the only place where you will find that are small fora. Big fora simply got big because many people like the lack of flamewars, argumenta ad infinitum, personal attacks, namecalling and so on.
Yes, some people will leave. If they can't handle a grown-up discussion; so be it.