I think they're trying to solve the same problems other discussion-related services have by approaching the problems from a different perspective: discussions a

I think they're trying to solve the same problems other discussion-related services have by approaching the problems from a different perspective: discussions are private by default, and therefore the participants have greater control of signal:noise. They're trying to build from the bottom up instead of top down and hopefully that solves the problems most people associate with discussion services (e.g., comments), particularly people who abuse the the system in various ways such as trolls, griefers, and spammers.