I think the largest group was around 20-30 when Kathy had a meet up at Figment one time. Otherwise touring is usually on your own and not done as a group. I know the team has mentioned impromptu meet ups in the parks for the MM, but I don't think it'll be anything involving hundreds of DISers congregating in one area. That's when they do DISapalooza and rent a space and attraction.
I hate to say it but that reminds me of the international tour groups' singing and chanting. It definitely disrupts the ambiance of a public location when a large group takes over like that. It makes it uncomfortable for others and takes away from the theming. This is why Disney has cracked down and no longer allows tour groups to chant, etc. I'm sure you had good intentions, but I would not appreciate that during my park visit.