antonjw You gave me a great idea. I will create a "Discussion Engine". But it will not be a software that is available, I will simply create a website but with the functionality you describe of a "Discussion Engine" that you propose, added to hundreds of ideas that I have been collecting in several well-organized documents. My project will be called "Hardsot".
But I will begin to create the code exactly after a year and a half, because I have too many occupations. Besides living in Venezuela, which complicates many things. I will be the next "Mark Zuckerberg". But improved version, I will integrate not only your ideas, but hundreds that I have read during my years on the internet, plus the ideas that I have had. This will be a bomb.
I think the "Chat" system should be equal to Facebook. Just chat with the users who are your "friends" in the community. Although there may be a global chat that is activated in "special events" of the general community. Have them split into different chat rooms. As simple as that.