I certainly see nothing on any of their pages to suggest that they ban more formal conferences. All their language is very broad and vague. The fact that "Organizer" is an official class of user who have to pay is a pretty strong indicator that it's not exclusively some loose informal thing.
Even in their terms of service, there's nothing that comes close to banning conferences. The only thing remotely related is that they disallow advertising commercial services.
Even in their terms of service, there's nothing that comes close to banning conferences. The only thing remotely related is that they disallow advertising commercial services.