But at what point does an service cross from being an platform in an competitive market to an crucial part of the infrastructure used by an society for communic

But at what point does an service cross from being an platform in an competitive market to an crucial part of the infrastructure used by an society for communication? If twitter/facebook is allowed to serve as a primary means for an government organisation/department to serve as the primary way which it communicate it's not to hard to argue that that line have been crossed where it have to act as an "open access" common carirer, from an pragmatic real world stand point. Putting an purely technical definition as the core of this debate is arguing over how many angels can fit on an pin needle, and not of any real value for deciding what kind of society we want.