Eh, a social group isn't a business gathering nor is it a calculated construct. We're talking about people following their natural attraction.

People don't consciously 'organise' a group with some 'group manager' and a nice hierarchy, technology choice panels, and acquisition procedures. There isn't some grand evil plan where the 'group CEO' selects the technology that everyone now has to use. This is just users using an end-user service on their end-user device that doesn't cause them friction and makes them happy.

People don't think "I want to send an instant message to my group-colleagues on their mobile OS on their mobile hardware over their WWAN link to setup a meeting in our shared calendar for a ninety minute gathering for a consumption of nutrients". They generally think: "I could go for a bite, I'll let my friends know so we could go together". Everything that makes that harder just gets thrown out.