Thanks for your answers. I've rarely seen folks communicating actively over itch.io community (in deed, I never saw it happen :-D). It's just not the same as a social platform. But I don't want to be the one pushing for having Discord for that. It's up to the organizer in my oppinion to decide, if you want to give exchange and communication a platform in your Jam. Of cause this is no guarentee for people to do so, but it's the best base I think.