Regardless of petty admin dickwaving from local groups, a game like this desperately needs some form of in-game communication. Given their added emphasis on socializing via trading you'd think a chat system would be in the pipeline somewhere, even if it's just sending simple, pre-made messages to nearby players (shout-outs asking for raid help, trade requests, battle requests should PvP be introduced).
Obviously they can't stop groups from forming on their own via social media, but a chat system - even a simple one - is something that would make sense for a game like PoGo to have.